diff --git a/bench/bench.py b/bench/bench.py
index 6593376be..e7c3a97e0 100644
--- a/bench/bench.py
+++ b/bench/bench.py
@@ -1,6 +1,6 @@
+import copy
 import fnmatch
 import os
-import copy
 from timeit import Timer
 
 import yaml
diff --git a/docs/_themes/flask_theme_support.py b/docs/_themes/flask_theme_support.py
index 0dcf53b75..64e249963 100644
--- a/docs/_themes/flask_theme_support.py
+++ b/docs/_themes/flask_theme_support.py
@@ -1,18 +1,18 @@
 # flasky extensions.  flasky pygments style based on tango style
 from pygments.style import Style
 from pygments.token import (
-    Keyword,
-    Name,
     Comment,
-    String,
     Error,
+    Generic,
+    Keyword,
+    Literal,
+    Name,
     Number,
     Operator,
-    Generic,
-    Whitespace,
-    Punctuation,
     Other,
-    Literal,
+    Punctuation,
+    String,
+    Whitespace,
 )
 
 
diff --git a/docs/conf.py b/docs/conf.py
index 2d740f327..211ff0b10 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python3
-# -*- coding: utf-8 -*-
 #
 # pint documentation build configuration file, created by
 # sphinx-quickstart on Thu Mar  1 13:33:14 2012.
@@ -12,9 +11,10 @@
 # All configuration values have a default; values that are commented out
 # serve to show the default.
 
-import pkg_resources
 import datetime
 
+import pkg_resources
+
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
@@ -60,7 +60,7 @@
 
 try:  # pragma: no cover
     version = pkg_resources.get_distribution(project).version
-except:  # pragma: no cover
+except Exception:  # pragma: no cover
     # we seem to have a local copy not installed without setuptools
     # so the reported version will be unknown
     version = "unknown"
@@ -200,11 +200,11 @@
 
 latex_elements = {
     # The paper size ('letterpaper' or 'a4paper').
-    #'papersize': 'letterpaper',
+    # 'papersize': 'letterpaper',
     # The font size ('10pt', '11pt' or '12pt').
-    #'pointsize': '10pt',
+    # 'pointsize': '10pt',
     # Additional stuff for the LaTeX preamble.
-    "preamble": "".join(("\DeclareUnicodeCharacter{2212}{-}",))  # MINUS
+    "preamble": "".join((r"\DeclareUnicodeCharacter{2212}{-}",))  # MINUS
 }
 
 # Grouping the document tree into LaTeX files. List of tuples
diff --git a/pint/__init__.py b/pint/__init__.py
index 7e27f55b2..682e4e717 100644
--- a/pint/__init__.py
+++ b/pint/__init__.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint
     ~~~~
@@ -12,6 +11,8 @@
     :license: BSD, see LICENSE for more details.
 """
 
+import sys
+
 import pkg_resources
 
 from .context import Context
@@ -26,24 +27,24 @@
 from .formatting import formatter
 from .measurement import Measurement
 from .quantity import Quantity
-from .registry import UnitRegistry, LazyRegistry
+from .registry import LazyRegistry, UnitRegistry
 from .unit import Unit
-from .util import pi_theorem, logger
-
-
-import sys
+from .util import logger, pi_theorem
 
 try:
-    from pintpandas import PintType, PintArray
+    from pintpandas import PintArray, PintType
+
+    del PintType
+    del PintArray
 
     _HAS_PINTPANDAS = True
-except Exception:
+except ImportError:
     _HAS_PINTPANDAS = False
     _, _pintpandas_error, _ = sys.exc_info()
 
 try:  # pragma: no cover
     __version__ = pkg_resources.get_distribution("pint").version
-except:  # pragma: no cover
+except Exception:  # pragma: no cover
     # we seem to have a local copy not installed without setuptools
     # so the reported version will be unknown
     __version__ = "unknown"
@@ -124,7 +125,9 @@ def test():
     "RedefinitionError",
     "UndefinedUnitError",
     "UnitStrippedWarning",
+    "formatter",
     "get_application_registry",
     "set_application_registry",
+    "pi_theorem",
     "__version__",
 )
diff --git a/pint/babel_names.py b/pint/babel_names.py
index e4bd1a002..9f23b8366 100644
--- a/pint/babel_names.py
+++ b/pint/babel_names.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.babel
     ~~~~~~~~~~
@@ -57,7 +56,7 @@
     millimeter="length-millimeter",
     metric_horsepower="power-horsepower",
     gibibyte="digital-gigabyte",
-    ## 'temperature-generic',
+    # 'temperature-generic',
     liter="volume-liter",
     turn="angle-revolution",
     microsecond="duration-microsecond",
@@ -111,7 +110,7 @@
     century="duration-century",
     cubic_foot="volume-cubic-foot",
     deciliter="volume-deciliter",
-    ##pint='volume-pint-metric',
+    # pint='volume-pint-metric',
     cubic_meter="volume-cubic-meter",
     cubic_kilometer="volume-cubic-kilometer",
     quart="volume-quart",
diff --git a/pint/compat.py b/pint/compat.py
index 3f7e49fb5..6f64acbfb 100644
--- a/pint/compat.py
+++ b/pint/compat.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.compat
     ~~~~~~~~~~~
@@ -9,10 +8,9 @@
     :license: BSD, see LICENSE for more details.
 """
 import tokenize
-import warnings
+from decimal import Decimal
 from io import BytesIO
 from numbers import Number
-from decimal import Decimal
 
 
 def tokenizer(input_string):
@@ -129,10 +127,12 @@ def _to_magnitude(value, force_ndarray=False):
     HAS_BABEL = False
 
 if not HAS_BABEL:
-    Loc = babel_units = None
+    Loc = babel_units = None  # noqa: F811
 
 # Define location of pint.Quantity in NEP-13 type cast hierarchy by defining upcast and
 # downcast/wrappable types
+
+
 def is_upcast_type(other):
     # Check if class name is in preset list
     return other.__class__.__name__ in ("PintArray", "Series", "DataArray")
diff --git a/pint/context.py b/pint/context.py
index e027864b1..db57336e5 100644
--- a/pint/context.py
+++ b/pint/context.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.context
     ~~~~~~~~~~~~
@@ -13,8 +12,8 @@
 import weakref
 from collections import ChainMap, defaultdict
 
-from .util import ParserHelper, UnitsContainer, to_units_container, SourceIterator
 from .errors import DefinitionSyntaxError
+from .util import ParserHelper, SourceIterator, to_units_container
 
 #: Regex to match the header parts of a context.
 _header_re = re.compile(
@@ -37,6 +36,7 @@ class Context:
     dimension to another. Each Dimension are specified using a UnitsContainer.
     Simple transformation are given with a function taking a single parameter.
 
+        >>> from pint.util import UnitsContainer
         >>> timedim = UnitsContainer({'[time]': 1})
         >>> spacedim = UnitsContainer({'[length]': 1})
         >>> def f(time):
@@ -106,10 +106,10 @@ def from_lines(cls, lines, to_base_func=None):
             else:
                 aliases = ()
             defaults = r.groupdict()["defaults"]
-        except:
+        except Exception as exc:
             raise DefinitionSyntaxError(
                 "Could not parse the Context header '%s'" % header, lineno=lineno
-            )
+            ) from exc
 
         if defaults:
 
@@ -123,11 +123,11 @@ def to_num(val):
             try:
                 defaults = (part.split("=") for part in defaults.strip("()").split(","))
                 defaults = {str(k).strip(): to_num(v) for k, v in defaults}
-            except (ValueError, TypeError):
+            except (ValueError, TypeError) as exc:
                 raise DefinitionSyntaxError(
                     f"Could not parse Context definition defaults: '{txt}'",
                     lineno=lineno,
-                )
+                ) from exc
 
             ctx = cls(name, aliases, defaults)
         else:
@@ -156,11 +156,11 @@ def to_num(val):
                     ctx.add_transformation(src, dst, func)
                 else:
                     raise Exception
-            except:
+            except Exception as exc:
                 raise DefinitionSyntaxError(
                     "Could not parse Context %s relation '%s'" % (name, line),
                     lineno=lineno,
-                )
+                ) from exc
 
         if defaults:
             missing_pars = defaults.keys() - set(names)
diff --git a/pint/converters.py b/pint/converters.py
index 62572f8ad..ff1624ce3 100644
--- a/pint/converters.py
+++ b/pint/converters.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.converters
     ~~~~~~~~~~~~~~~
diff --git a/pint/definitions.py b/pint/definitions.py
index e6ad101cb..0ca7ed4fc 100644
--- a/pint/definitions.py
+++ b/pint/definitions.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.definitions
     ~~~~~~~~~~~~~~~~
@@ -9,8 +8,8 @@
     :license: BSD, see LICENSE for more details.
 """
 
-from .converters import ScaleConverter, OffsetConverter
-from .util import UnitsContainer, _is_dim, ParserHelper
+from .converters import OffsetConverter, ScaleConverter
+from .util import ParserHelper, UnitsContainer, _is_dim
 
 
 class Definition:
diff --git a/pint/errors.py b/pint/errors.py
index d5ae803f0..c0d9ab7ae 100644
--- a/pint/errors.py
+++ b/pint/errors.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.errors
     ~~~~~~~~~~~
diff --git a/pint/formatting.py b/pint/formatting.py
index 931e15414..2564030de 100644
--- a/pint/formatting.py
+++ b/pint/formatting.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.formatter
     ~~~~~~~~~~~~~~
@@ -11,7 +10,7 @@
 
 import re
 
-from .babel_names import _babel_units, _babel_lengths
+from .babel_names import _babel_lengths, _babel_units
 from .compat import Loc
 
 __JOIN_REG_EXP = re.compile(r"\{\d*\}")
@@ -43,7 +42,7 @@ def _pretty_fmt_exponent(num):
     """Format an number into a pretty printed exponent.
     """
     # TODO: Will not work for decimals
-    ret = "{0:n}".format(num).replace("-", "⁻")
+    ret = f"{num:n}".replace("-", "⁻")
     for n in range(10):
         ret = ret.replace(str(n), _PRETTY_EXPONENTS[n])
     return ret
@@ -104,7 +103,7 @@ def formatter(
     division_fmt=" / ",
     power_fmt="{} ** {}",
     parentheses_fmt="({0})",
-    exp_call=lambda x: "{0:n}".format(x),
+    exp_call=lambda x: f"{x:n}",
     locale=None,
     babel_length="long",
     babel_plural_form="one",
@@ -266,7 +265,7 @@ def _tothe(power):
         # remove unit prefix if it exists
         # siunitx supports \prefix commands
 
-        l = lpos if power >= 0 else lneg
+        lpick = lpos if power >= 0 else lneg
         prefix = None
         for p in registry._prefixes.values():
             p = str(p)
@@ -275,11 +274,11 @@ def _tothe(power):
                 unit = unit.replace(prefix, "", 1)
 
         if power < 0:
-            l.append(r"\per")
+            lpick.append(r"\per")
         if prefix is not None:
-            l.append(r"\{}".format(prefix))
-        l.append(r"\{}".format(unit))
-        l.append(r"{}".format(_tothe(abs(power))))
+            lpick.append(r"\{}".format(prefix))
+        lpick.append(r"\{}".format(unit))
+        lpick.append(r"{}".format(_tothe(abs(power))))
 
     return "".join(lpos) + "".join(lneg)
 
diff --git a/pint/matplotlib.py b/pint/matplotlib.py
index 2390677f0..3b7b0af90 100644
--- a/pint/matplotlib.py
+++ b/pint/matplotlib.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.matplotlib
     ~~~~~~~~~~~~~~~
diff --git a/pint/measurement.py b/pint/measurement.py
index 54df1d802..98ba7a575 100644
--- a/pint/measurement.py
+++ b/pint/measurement.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.measurement
     ~~~~~~~~~~~~~~~~
@@ -76,7 +75,7 @@ def __repr__(self):
         )
 
     def __str__(self):
-        return "{0}".format(self)
+        return "{}".format(self)
 
     def __format__(self, spec):
         # special cases
diff --git a/pint/numpy_func.py b/pint/numpy_func.py
index 52d791dea..75a4de6a6 100644
--- a/pint/numpy_func.py
+++ b/pint/numpy_func.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.numpy_func
     ~~~~~~~~~~~~~~~
@@ -7,12 +6,12 @@
     :license: BSD, see LICENSE for more details.
 """
 
+import warnings
 from inspect import signature
 from itertools import chain
-import warnings
 
-from .compat import NP_NO_VALUE, is_upcast_type, np, eq
-from .errors import DimensionalityError, UnitStrippedWarning
+from .compat import eq, is_upcast_type, np
+from .errors import DimensionalityError
 from .util import iterable, sized
 
 HANDLED_UFUNCS = {}
@@ -92,8 +91,8 @@ def convert_to_consistent_units(*args, pre_calc_units=None, **kwargs):
 def unwrap_and_wrap_consistent_units(*args):
     """Strip units from args while providing a rewrapping function.
 
-    Returns the given args as parsed by convert_to_consistent_units assuming units of first
-    arg with units, along with a wrapper to restore that unit to the output.
+    Returns the given args as parsed by convert_to_consistent_units assuming units of
+    first arg with units, along with a wrapper to restore that unit to the output.
     """
     first_input_units = _get_first_input_units(args)
     args, _ = convert_to_consistent_units(*args, pre_calc_units=first_input_units)
@@ -167,7 +166,9 @@ def get_op_output_unit(unit_op, first_input_units, all_args=[], size=None):
 
 
 def implements(numpy_func_string, func_type):
-    """Register an __array_function__/__array_ufunc__ implementation for Quantity objects."""
+    """Register an __array_function__/__array_ufunc__ implementation for Quantity
+    objects.
+    """
 
     def decorator(func):
         if func_type == "function":
@@ -198,8 +199,8 @@ def implementation(*args, **kwargs):
                 *args, pre_calc_units=first_input_units, **kwargs
             )
         else:
-            # Match all input args/kwargs to input_units, or if input_units is None, simply
-            # strip units
+            # Match all input args/kwargs to input_units, or if input_units is None,
+            # simply strip units
             stripped_args, stripped_kwargs = convert_to_consistent_units(
                 *args, pre_calc_units=input_units, **kwargs
             )
@@ -237,19 +238,19 @@ def implementation(*args, **kwargs):
 Define ufunc behavior collections.
 
 - `strip_unit_input_output_ufuncs`: units should be ignored on both input and output
-- `matching_input_bare_output_ufuncs`: inputs are converted to matching units, but outputs are
-  returned as-is
-- `matching_input_set_units_output_ufuncs`: inputs are converted to matching units, and the
-  output units are as set by the dict value
-- `set_units_ufuncs`: dict values are specified as (in_unit, out_unit), so that inputs are
-  converted to in_unit before having magnitude passed to NumPy ufunc, and outputs are set to
-  have out_unit
+- `matching_input_bare_output_ufuncs`: inputs are converted to matching units, but
+   outputs are returned as-is
+- `matching_input_set_units_output_ufuncs`: inputs are converted to matching units, and
+  the output units are as set by the dict value
+- `set_units_ufuncs`: dict values are specified as (in_unit, out_unit), so that inputs
+  are converted to in_unit before having magnitude passed to NumPy ufunc, and outputs
+  are set to have out_unit
 - `matching_input_copy_units_output_ufuncs`: inputs are converted to matching units, and
   outputs are set to that unit
-- `copy_units_output_ufuncs`: input units (except the first) are ignored, and output is set to
-  that of the first input unit
-- `op_units_output_ufuncs`: determine output unit from input unit as determined by operation
-  (see `get_op_output_unit`)
+- `copy_units_output_ufuncs`: input units (except the first) are ignored, and output is
+  set to that of the first input unit
+- `op_units_output_ufuncs`: determine output unit from input unit as determined by
+  operation (see `get_op_output_unit`)
 """
 strip_unit_input_output_ufuncs = ["isnan", "isinf", "isfinite", "signbit"]
 matching_input_bare_output_ufuncs = [
@@ -289,9 +290,10 @@ def implementation(*args, **kwargs):
     "logaddexp": ("", ""),
     "logaddexp2": ("", ""),
 }
-# TODO (#905 follow-up): while this matches previous behavior, some of these have optional
-# arguments that should not be Quantities. This should be fixed, and tests using these
-# optional arguments should be added.
+# TODO (#905 follow-up):
+#   while this matches previous behavior, some of these have optional arguments that
+#   should not be Quantities. This should be fixed, and tests using these optional
+#   arguments should be added.
 matching_input_copy_units_output_ufuncs = [
     "compress",
     "conj",
@@ -398,9 +400,9 @@ def _power(x1, x2):
 
 
 def _add_subtract_handle_non_quantity_zero(x1, x2):
-    # As in #121/#122, if a value is 0 (but not Quantity 0) do the operation without checking
-    # units. We do the calculation instead of just returning the same value to enforce any
-    # shape checking and type casting due to the operation.
+    # As in #121/#122, if a value is 0 (but not Quantity 0) do the operation without
+    # checking units. We do the calculation instead of just returning the same value to
+    # enforce any shape checking and type casting due to the operation.
     if eq(x1, 0, True):
         (x2,), output_wrap = unwrap_and_wrap_consistent_units(x2)
     elif eq(x2, 0, True):
@@ -546,8 +548,8 @@ def _isin(element, test_elements, assume_unique=False, invert=False):
             try:
                 compatible_test_elements.append(test_element.m_as(element.units))
             except DimensionalityError:
-                # Incompatible unit test elements cannot be in element, but others in sequence
-                # may
+                # Incompatible unit test elements cannot be in element, but others in
+                # sequence may
                 pass
         test_elements = compatible_test_elements
     else:
@@ -679,8 +681,8 @@ def implementation(*arrays):
         "function", func_str, input_units="all_consistent", output_unit="match_input"
     )
 
-# Handle cumulative products (which must be dimensionless for consistent units across output
-# array)
+# Handle cumulative products (which must be dimensionless for consistent units across
+# output array)
 for func_str in ["cumprod", "cumproduct", "nancumprod"]:
     implement_func(
         "function", func_str, input_units="dimensionless", output_unit="match_input"
diff --git a/pint/pint_eval.py b/pint/pint_eval.py
index f7e08a218..afa3877f9 100644
--- a/pint/pint_eval.py
+++ b/pint/pint_eval.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.pint_eval
     ~~~~~~~~~~~~~~
@@ -10,7 +9,6 @@
 """
 
 import operator
-
 import token as tokenlib
 
 from .errors import DefinitionSyntaxError
@@ -95,10 +93,11 @@ def build_eval_tree(tokens, op_priority=_OP_PRIORITY, index=0, depth=0, prev_op=
     Params:
     Index, depth, and prev_op used recursively, so don't touch.
     Tokens is an iterable of tokens from an expression to be evaluated.
-    
-    Transform the tokens from an expression into a recursive parse tree, following order of operations.
-    Operations can include binary ops (3 + 4), implicit ops (3 kg), or unary ops (-1).
-    
+
+    Transform the tokens from an expression into a recursive parse tree, following order
+    of operations. Operations can include binary ops (3 + 4), implicit ops (3 kg), or
+    unary ops (-1).
+
     General Strategy:
     1) Get left side of operator
     2) If no tokens left, return final result
@@ -109,7 +108,7 @@ def build_eval_tree(tokens, op_priority=_OP_PRIORITY, index=0, depth=0, prev_op=
     6) Go back to step #2
     """
 
-    if depth == 0 and prev_op == None:
+    if depth == 0 and prev_op is None:
         # ensure tokens is list so we can access by index
         tokens = list(tokens)
 
@@ -147,9 +146,10 @@ def build_eval_tree(tokens, op_priority=_OP_PRIORITY, index=0, depth=0, prev_op=
                     result = right
             elif token_text in op_priority:
                 if result:
-                    # equal-priority operators are grouped in a left-to-right order, unless they're
-                    # exponentiation, in which case they're grouped right-to-left
-                    # this allows us to get the expected behavior for multiple exponents
+                    # equal-priority operators are grouped in a left-to-right order,
+                    # unless they're exponentiation, in which case they're grouped
+                    # right-to-left this allows us to get the expected behavior for
+                    # multiple exponents
                     #     (2^3^4)  --> (2^(3^4))
                     #     (2 * 3 / 4) --> ((2 * 3) / 4)
                     if op_priority[token_text] <= op_priority.get(
@@ -174,7 +174,8 @@ def build_eval_tree(tokens, op_priority=_OP_PRIORITY, index=0, depth=0, prev_op=
             if result:
                 # tokens with an implicit operation i.e. "1 kg"
                 if op_priority[""] <= op_priority.get(prev_op, -1):
-                    # previous operator is higher priority than implicit, so end previous binary op
+                    # previous operator is higher priority than implicit, so end
+                    # previous binary op
                     return result, index - 1
                 right, index = build_eval_tree(
                     tokens, op_priority, index, depth + 1, ""
diff --git a/pint/quantity.py b/pint/quantity.py
index 1aff1c238..627e3f216 100644
--- a/pint/quantity.py
+++ b/pint/quantity.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.quantity
     ~~~~~~~~~~~~~
@@ -21,53 +20,49 @@
 
 from pkg_resources.extern.packaging import version
 
-from .formatting import (
-    remove_custom_flags,
-    siunitx_format_unit,
-    ndarray_to_latex,
-    ndarray_to_latex_parts,
+from .compat import SKIP_ARRAY_FUNCTION_CHANGE_WARNING  # noqa: F401
+from .compat import (
+    NUMPY_VER,
+    BehaviorChangeWarning,
+    Loc,
+    _to_magnitude,
+    array_function_change_msg,
+    eq,
+    is_upcast_type,
+    ndarray,
+    np,
 )
+from .definitions import UnitDefinition
 from .errors import (
     DimensionalityError,
     OffsetUnitCalculusError,
     PintTypeError,
-    UndefinedUnitError,
     UnitStrippedWarning,
 )
-from .definitions import UnitDefinition
-from .compat import (
-    Loc,
-    NUMPY_VER,
-    SKIP_ARRAY_FUNCTION_CHANGE_WARNING,
-    BehaviorChangeWarning,
-    ndarray,
-    np,
-    _to_magnitude,
-    is_upcast_type,
-    eq,
-    array_function_change_msg,
-)
-from .util import (
-    PrettyIPython,
-    logger,
-    UnitsContainer,
-    SharedRegistryObject,
-    to_units_container,
-    infer_base_unit,
-    iterable,
-    sized,
+from .formatting import (
+    ndarray_to_latex,
+    ndarray_to_latex_parts,
+    remove_custom_flags,
+    siunitx_format_unit,
 )
 from .numpy_func import (
     HANDLED_UFUNCS,
     copy_units_output_ufuncs,
     get_op_output_unit,
-    matching_input_bare_output_ufuncs,
     matching_input_copy_units_output_ufuncs,
     matching_input_set_units_output_ufuncs,
     numpy_wrap,
     op_units_output_ufuncs,
     set_units_ufuncs,
 )
+from .util import (
+    PrettyIPython,
+    SharedRegistryObject,
+    UnitsContainer,
+    infer_base_unit,
+    logger,
+    to_units_container,
+)
 
 
 class _Exception(Exception):  # pragma: no cover
@@ -404,7 +399,7 @@ def check(self, dimension):
 
     @classmethod
     def from_list(cls, quant_list, units=None):
-        """Transforms a list of Quantities into an numpy.array quantity. 
+        """Transforms a list of Quantities into an numpy.array quantity.
         If no units are specified, the unit of the first element will be used.
         Same as from_sequence.
 
@@ -420,7 +415,7 @@ def from_list(cls, quant_list, units=None):
 
     @classmethod
     def from_sequence(cls, seq, units=None):
-        """Transforms a sequence of Quantities into an numpy.array quantity. 
+        """Transforms a sequence of Quantities into an numpy.array quantity.
         If no units are specified, the unit of the first element will be used.
 
         If units is not specified and sequence is empty, the unit cannot be determined
@@ -616,7 +611,7 @@ def to_compact(self, unit=None):
                 log10_scale = int(math.log10(scale))
                 if log10_scale == math.log10(scale):
                     SI_prefixes[log10_scale] = prefix.name
-            except:
+            except Exception:
                 SI_prefixes[0] = ""
 
         SI_prefixes = sorted(SI_prefixes.items())
@@ -1442,30 +1437,30 @@ def _numpy_method_wrap(self, func, *args, **kwargs):
             return value
 
     def clip(self, first=None, second=None, out=None, **kwargs):
-        min = kwargs.get("min", first)
-        max = kwargs.get("max", second)
+        minimum = kwargs.get("min", first)
+        maximum = kwargs.get("max", second)
 
-        if min is None and max is None:
+        if minimum is None and maximum is None:
             raise TypeError("clip() takes at least 3 arguments (2 given)")
 
-        if max is None and "min" not in kwargs:
-            min, max = max, min
+        if maximum is None and "min" not in kwargs:
+            minimum, maximum = maximum, minimum
 
         kwargs = {"out": out}
 
-        if min is not None:
-            if isinstance(min, self.__class__):
-                kwargs["min"] = min.to(self).magnitude
+        if minimum is not None:
+            if isinstance(minimum, self.__class__):
+                kwargs["min"] = minimum.to(self).magnitude
             elif self.dimensionless:
-                kwargs["min"] = min
+                kwargs["min"] = minimum
             else:
                 raise DimensionalityError("dimensionless", self._units)
 
-        if max is not None:
-            if isinstance(max, self.__class__):
-                kwargs["max"] = max.to(self).magnitude
+        if maximum is not None:
+            if isinstance(maximum, self.__class__):
+                kwargs["max"] = maximum.to(self).magnitude
             elif self.dimensionless:
-                kwargs["max"] = max
+                kwargs["max"] = maximum
             else:
                 raise DimensionalityError("dimensionless", self._units)
 
diff --git a/pint/registry.py b/pint/registry.py
index 0cb585b54..444b3631a 100644
--- a/pint/registry.py
+++ b/pint/registry.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.registry
     ~~~~~~~~~~~~~
@@ -33,54 +32,52 @@
 """
 
 import copy
-import os
-import re
-import math
 import functools
 import itertools
-import pkg_resources
+import math
+import os
+import re
+from collections import defaultdict
+from contextlib import closing, contextmanager
 from decimal import Decimal
 from fractions import Fraction
-from contextlib import contextmanager, closing
-from io import open, StringIO
-from collections import defaultdict
-from tokenize import NUMBER, NAME
+from io import StringIO
+from tokenize import NAME, NUMBER
 
-from . import registry_helpers
-from .context import Context, ContextChain
-from .util import (
-    getattr_maybe_raise,
-    logger,
-    pi_theorem,
-    solve_dependencies,
-    ParserHelper,
-    string_preprocessor,
-    find_connected_nodes,
-    find_shortest_path,
-    UnitsContainer,
-    _is_dim,
-    to_units_container,
-    SourceIterator,
-)
+import pkg_resources
 
+from . import registry_helpers, systems
 from .compat import tokenizer
+from .context import Context, ContextChain
+from .converters import ScaleConverter
 from .definitions import (
+    AliasDefinition,
     Definition,
-    UnitDefinition,
-    PrefixDefinition,
     DimensionDefinition,
-    AliasDefinition,
+    PrefixDefinition,
+    UnitDefinition,
 )
-from .converters import ScaleConverter
 from .errors import (
-    DimensionalityError,
-    UndefinedUnitError,
     DefinitionSyntaxError,
+    DimensionalityError,
     RedefinitionError,
+    UndefinedUnitError,
 )
-
 from .pint_eval import build_eval_tree
-from . import systems
+from .util import (
+    ParserHelper,
+    SourceIterator,
+    UnitsContainer,
+    _is_dim,
+    find_connected_nodes,
+    find_shortest_path,
+    getattr_maybe_raise,
+    logger,
+    pi_theorem,
+    solve_dependencies,
+    string_preprocessor,
+    to_units_container,
+)
 
 _BLOCK_RE = re.compile(r" |\(")
 
@@ -115,6 +112,7 @@ class BaseRegistry(metaclass=RegistryMeta):
     """Base class for all registries.
 
     Capabilities:
+
     - Register units, prefixes, and dimensions, and their relations.
     - Convert between units.
     - Find dimensionality of a unit.
@@ -123,17 +121,22 @@ class BaseRegistry(metaclass=RegistryMeta):
     - Parse a definition file.
     - Allow extending the definition file parser by registering @ directives.
 
-    :param filename: path of the units definition file to load or line iterable object.
-                     Empty to load the default definition file.
-                     None to leave the UnitRegistry empty.
-    :type filename: str or None
-    :param force_ndarray: convert any input, scalar or not to a numpy.ndarray.
-    :param on_redefinition: action to take in case a unit is redefined.
-                            'warn', 'raise', 'ignore'
-    :type on_redefinition: str
-    :param auto_reduce_dimensions: If True, reduce dimensionality on appropriate operations.
-    :param preprocessors: list of callables which are iteratively ran on any input expression
-                          or unit string
+    :param filename:
+        path of the units definition file to load or line iterable object. Empty to load
+        the default definition file. None to leave the UnitRegistry empty.
+    :type filename:
+        str or None
+    :param force_ndarray:
+        convert any input, scalar or not to a numpy.ndarray.
+    :param on_redefinition:
+        action to take in case a unit is redefined: 'warn', 'raise', 'ignore'
+    :type on_redefinition:
+        str
+    :param auto_reduce_dimensions:
+        If True, reduce dimensionality on appropriate operations.
+    :param preprocessors:
+        list of callables which are iteratively ran on any input expression or unit
+        string
     """
 
     #: Map context prefix to function
@@ -167,7 +170,6 @@ def __init__(
         auto_reduce_dimensions=False,
         preprocessors=None,
     ):
-
         self._register_parsers()
         self._init_dynamic_classes()
 
@@ -181,7 +183,8 @@ def __init__(
         #: Determines if dimensionality should be reduced on appropriate operations.
         self.auto_reduce_dimensions = auto_reduce_dimensions
 
-        #: Map between name (string) and value (string) of defaults stored in the definitions file.
+        #: Map between name (string) and value (string) of defaults stored in the
+        #: definitions file.
         self._defaults = {}
 
         #: Map dimension name (string) to its definition (DimensionDefinition).
@@ -191,7 +194,8 @@ def __init__(
         #: Might contain prefixed units.
         self._units = {}
 
-        #: Map unit name in lower case (string) to a set of unit names with the right case.
+        #: Map unit name in lower case (string) to a set of unit names with the right
+        #: case.
         #: Does not contain prefixed units.
         #: e.g: 'hz' - > set('Hz', )
         self._units_casei = defaultdict(set)
@@ -1048,9 +1052,9 @@ def _is_multiplicative(self, u):
         # If the unit is not in the registry might be because it is not
         # registered with its prefixed version.
         # TODO: Might be better to register them.
-        l = self._dedup_candidates(self.parse_unit_name(u))
+        candidates = self._dedup_candidates(self.parse_unit_name(u))
         try:
-            u = l[0][1]
+            u = candidates[0][1]
             return self._units[u].is_multiplicative
         except KeyError:
             raise UndefinedUnitError(u)
diff --git a/pint/registry_helpers.py b/pint/registry_helpers.py
index 9fd3f752a..07877ba4a 100644
--- a/pint/registry_helpers.py
+++ b/pint/registry_helpers.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.registry_helpers
     ~~~~~~~~~~~~~~~~~~~~~
@@ -14,7 +13,7 @@
 from itertools import zip_longest
 
 from .errors import DimensionalityError
-from .util import to_units_container, UnitsContainer
+from .util import UnitsContainer, to_units_container
 
 
 def _replace_units(original_units, values_by_name):
diff --git a/pint/systems.py b/pint/systems.py
index 4ae836041..35752687c 100644
--- a/pint/systems.py
+++ b/pint/systems.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.systems
     ~~~~~~~~~~~~
@@ -11,17 +10,18 @@
 
 import re
 
+from pint.compat import Loc
+
+from .babel_names import _babel_systems
 from .definitions import Definition, UnitDefinition
 from .errors import DefinitionSyntaxError, RedefinitionError
 from .util import (
-    to_units_container,
-    getattr_maybe_raise,
     SharedRegistryObject,
     SourceIterator,
+    getattr_maybe_raise,
     logger,
+    to_units_container,
 )
-from .babel_names import _babel_systems
-from pint.compat import Loc
 
 
 class Group(SharedRegistryObject):
diff --git a/pint/testsuite/__init__.py b/pint/testsuite/__init__.py
index ffcfbf1a4..a1e51d92e 100644
--- a/pint/testsuite/__init__.py
+++ b/pint/testsuite/__init__.py
@@ -1,17 +1,14 @@
-# -*- coding: utf-8 -*-
-
 import doctest
 import logging
+import math
 import os
 import unittest
-
 from contextlib import contextmanager
+from logging.handlers import BufferingHandler
 
+from pint import Quantity, UnitRegistry, logger
 from pint.compat import ndarray, np
-
-from pint import logger, UnitRegistry, Quantity
 from pint.testsuite.helpers import PintOutputChecker
-from logging.handlers import BufferingHandler
 
 
 class TestHandler(BufferingHandler):
@@ -43,10 +40,10 @@ def capture_log(self, level=logging.DEBUG):
         th.setLevel(level)
         logger.addHandler(th)
         if self._test_handler is not None:
-            l = len(self._test_handler.buffer)
+            buflen = len(self._test_handler.buffer)
         yield th.buffer
         if self._test_handler is not None:
-            self._test_handler.buffer = self._test_handler.buffer[:l]
+            self._test_handler.buffer = self._test_handler.buffer[:buflen]
 
     def setUp(self):
         self._test_handler = None
@@ -58,9 +55,8 @@ def setUp(self):
     def tearDown(self):
         if self._test_handler is not None:
             buf = self._test_handler.buffer
-            l = len(buf)
             msg = "\n".join(record.get("msg", str(record)) for record in buf)
-            self.assertEqual(l, 0, msg="%d warnings raised.\n%s" % (l, msg))
+            self.assertEqual(len(buf), 0, msg=f"{len(buf)} warnings raised.\n{msg}")
 
 
 class QuantityTestCase(BaseTestCase):
@@ -129,7 +125,8 @@ def testsuite():
     # TESTING THE DOCUMENTATION requires pyyaml, serialize, numpy and uncertainties
     if HAS_NUMPY and HAS_UNCERTAINTIES:
         try:
-            import yaml, serialize
+            import serialize  # noqa: F401
+            import yaml  # noqa: F401
 
             add_docs(suite)
         except ImportError:
@@ -155,8 +152,6 @@ def run():
     return test_runner.run(testsuite())
 
 
-import math
-
 _GLOBS = {
     "wrapping.rst": {
         "pendulum_period": lambda length: 2 * math.pi * math.sqrt(length / 9.806650),
diff --git a/pint/testsuite/helpers.py b/pint/testsuite/helpers.py
index a6cb78ccb..5a9139146 100644
--- a/pint/testsuite/helpers.py
+++ b/pint/testsuite/helpers.py
@@ -1,15 +1,13 @@
-# -*- coding: utf-8 -*-
-
 import doctest
-from distutils.version import StrictVersion
 import re
 import unittest
+from distutils.version import StrictVersion
 
 from ..compat import (
-    HAS_NUMPY,
     HAS_BABEL,
-    HAS_UNCERTAINTIES,
+    HAS_NUMPY,
     HAS_NUMPY_ARRAY_FUNCTION,
+    HAS_UNCERTAINTIES,
     NUMPY_VER,
 )
 
@@ -106,7 +104,7 @@ def check_output(self, want, got, optionflags):
         try:
             if eval(want) == eval(got):
                 return True
-        except:
+        except Exception:
             pass
 
         for regex in (_q_re, _sq_re):
@@ -124,7 +122,7 @@ def check_output(self, want, got, optionflags):
                     return False
 
                 return True
-            except:
+            except Exception:
                 pass
 
         cnt = 0
@@ -138,7 +136,7 @@ def check_output(self, want, got, optionflags):
                 if parsed_got == parsed_want:
                     return True
 
-            except:
+            except Exception:
                 pass
 
         if cnt:
diff --git a/pint/testsuite/parameterized.py b/pint/testsuite/parameterized.py
index 239610501..ca0a72442 100644
--- a/pint/testsuite/parameterized.py
+++ b/pint/testsuite/parameterized.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-#
 # Adds Parameterized tests for Python's unittest module
 #
 # Code from: parameterizedtestcase, version: 0.1.0
@@ -23,11 +21,10 @@
 #        def test_eval(self, input, expected_output):
 #            self.assertEqual(eval(input), expected_output)
 
+import unittest
 from collections.abc import Callable
 from functools import wraps
 
-import unittest
-
 
 def augment_method_docstring(
     method, new_class_dict, classname, param_names, param_values, new_method
diff --git a/pint/testsuite/test_application_registry.py b/pint/testsuite/test_application_registry.py
index b0f77ebc1..923304c68 100644
--- a/pint/testsuite/test_application_registry.py
+++ b/pint/testsuite/test_application_registry.py
@@ -11,7 +11,6 @@
     get_application_registry,
     set_application_registry,
 )
-
 from pint.testsuite import BaseTestCase
 from pint.testsuite.helpers import requires_uncertainties
 
diff --git a/pint/testsuite/test_babel.py b/pint/testsuite/test_babel.py
index 2210fe706..67bc22ed4 100644
--- a/pint/testsuite/test_babel.py
+++ b/pint/testsuite/test_babel.py
@@ -1,8 +1,7 @@
-# -*- coding: utf-8 -*-
+import os
 
-from pint.testsuite import helpers, BaseTestCase
 from pint import UnitRegistry
-import os
+from pint.testsuite import BaseTestCase, helpers
 
 
 class TestBabel(BaseTestCase):
diff --git a/pint/testsuite/test_contexts.py b/pint/testsuite/test_contexts.py
index 5fd6598da..1b072757f 100644
--- a/pint/testsuite/test_contexts.py
+++ b/pint/testsuite/test_contexts.py
@@ -1,12 +1,10 @@
-# -*- coding: utf-8 -*-
-
 import itertools
 from collections import defaultdict
 
-from pint import UnitRegistry, DefinitionSyntaxError, DimensionalityError
+from pint import DefinitionSyntaxError, DimensionalityError, UnitRegistry
 from pint.context import Context
-from pint.util import UnitsContainer
 from pint.testsuite import QuantityTestCase
+from pint.util import UnitsContainer
 
 
 def add_ctxs(ureg):
@@ -117,7 +115,7 @@ def test_known_context_enable(self):
     def test_graph(self):
         ureg = UnitRegistry()
         add_ctxs(ureg)
-        l = UnitsContainer({"[length]": 1.0})
+        l = UnitsContainer({"[length]": 1.0})  # noqa: E741
         t = UnitsContainer({"[time]": -1.0})
         c = UnitsContainer({"[current]": 1.0})
 
@@ -156,7 +154,7 @@ def test_graph(self):
     def test_graph_enable(self):
         ureg = UnitRegistry()
         add_ctxs(ureg)
-        l = UnitsContainer({"[length]": 1.0})
+        l = UnitsContainer({"[length]": 1.0})  # noqa: E741
         t = UnitsContainer({"[time]": -1.0})
         c = UnitsContainer({"[current]": 1.0})
 
@@ -224,14 +222,9 @@ def test_known_nested_context(self):
     def test_unknown_context(self):
         ureg = UnitRegistry()
         add_ctxs(ureg)
-        try:
+        with self.assertRaises(KeyError):
             with ureg.context("la"):
                 pass
-        except KeyError as e:
-            value = True
-        except Exception as e:
-            value = False
-        self.assertTrue(value)
         self.assertFalse(ureg._active_ctx)
         self.assertFalse(ureg._active_ctx.graph)
 
@@ -242,15 +235,9 @@ def test_unknown_nested_context(self):
         with ureg.context("lc"):
             x = dict(ureg._active_ctx)
             y = dict(ureg._active_ctx.graph)
-            try:
+            with self.assertRaises(KeyError):
                 with ureg.context("la"):
                     pass
-            except KeyError as e:
-                value = True
-            except Exception as e:
-                value = False
-
-            self.assertTrue(value)
 
             self.assertEqual(x, ureg._active_ctx)
             self.assertEqual(y, ureg._active_ctx.graph)
diff --git a/pint/testsuite/test_converters.py b/pint/testsuite/test_converters.py
index 7fadc0073..061b05da8 100644
--- a/pint/testsuite/test_converters.py
+++ b/pint/testsuite/test_converters.py
@@ -1,10 +1,8 @@
-# -*- coding: utf-8 -*-
-
 import itertools
 
 from pint.compat import np
-from pint.converters import ScaleConverter, OffsetConverter, Converter
-from pint.testsuite import helpers, BaseTestCase
+from pint.converters import Converter, OffsetConverter, ScaleConverter
+from pint.testsuite import BaseTestCase, helpers
 
 
 class TestConverter(BaseTestCase):
diff --git a/pint/testsuite/test_definitions.py b/pint/testsuite/test_definitions.py
index 8f30a45c5..421bdb8d8 100644
--- a/pint/testsuite/test_definitions.py
+++ b/pint/testsuite/test_definitions.py
@@ -1,16 +1,13 @@
-# -*- coding: utf-8 -*-
-
-from pint.util import UnitsContainer
-from pint.converters import ScaleConverter, OffsetConverter
+from pint.converters import OffsetConverter, ScaleConverter
 from pint.definitions import (
+    AliasDefinition,
     Definition,
+    DimensionDefinition,
     PrefixDefinition,
     UnitDefinition,
-    DimensionDefinition,
-    AliasDefinition,
 )
-
 from pint.testsuite import BaseTestCase
+from pint.util import UnitsContainer
 
 
 class TestDefinition(BaseTestCase):
diff --git a/pint/testsuite/test_errors.py b/pint/testsuite/test_errors.py
index 56ae7528b..cb75dd7ca 100644
--- a/pint/testsuite/test_errors.py
+++ b/pint/testsuite/test_errors.py
@@ -1,12 +1,10 @@
-# -*- coding: utf-8 -*-
-
 import pickle
 
 from pint import (
     DefinitionSyntaxError,
     DimensionalityError,
-    Quantity,
     OffsetUnitCalculusError,
+    Quantity,
     RedefinitionError,
     UndefinedUnitError,
     UnitRegistry,
diff --git a/pint/testsuite/test_formatter.py b/pint/testsuite/test_formatter.py
index cf5e64b44..c4a4d5766 100644
--- a/pint/testsuite/test_formatter.py
+++ b/pint/testsuite/test_formatter.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 from pint import formatting as fmt
 from pint.testsuite import QuantityTestCase
 
diff --git a/pint/testsuite/test_issues.py b/pint/testsuite/test_issues.py
index b61abf595..145d0cc9b 100644
--- a/pint/testsuite/test_issues.py
+++ b/pint/testsuite/test_issues.py
@@ -1,16 +1,13 @@
-# -*- coding: utf-8 -*-
-
 import copy
 import math
-import unittest
 import pprint
+import unittest
 
 from pint import DimensionalityError, UnitRegistry
-from pint.unit import UnitsContainer
-from pint.util import ParserHelper
-
 from pint.compat import np
 from pint.testsuite import QuantityTestCase, helpers
+from pint.unit import UnitsContainer
+from pint.util import ParserHelper
 
 
 class TestIssues(QuantityTestCase):
@@ -265,12 +262,7 @@ def test_issue85(self):
         m = 1.0 * ureg.amu
         va = 2.0 * ureg.k * T / m
 
-        try:
-            va.to_base_units()
-        except:
-            self.assertTrue(
-                False, "Error while trying to get base units for {}".format(va)
-            )
+        va.to_base_units()
 
         boltmk = 1.380649e-23 * ureg.J / ureg.K
         vb = 2.0 * boltmk * T / m
@@ -391,11 +383,11 @@ def test_issue105(self):
 
         for func in (ureg.get_name, ureg.parse_expression):
             val = func("meter")
-            self.assertRaises(AttributeError, func, "METER")
+            with self.assertRaises(AttributeError):
+                func("METER")
             self.assertEqual(val, func("METER", False))
 
     def test_issue121(self):
-        sh = (2, 1)
         ureg = UnitRegistry()
         z, v = 0, 2.0
         self.assertEqual(z + v * ureg.meter, v * ureg.meter)
@@ -426,16 +418,10 @@ def test_issue121b(self):
 
         z, v = np.zeros((3, 1)), 2.0 * np.ones(sh)
         for x, y in ((z, v), (z, v * ureg.meter), (v * ureg.meter, z)):
-            try:
-                w = x + y
-                self.assertTrue(False, "ValueError not raised")
-            except ValueError:
-                pass
-            try:
-                w = x - y
-                self.assertTrue(False, "ValueError not raised")
-            except ValueError:
-                pass
+            with self.assertRaises(ValueError):
+                x + y
+            with self.assertRaises(ValueError):
+                x - y
 
     @helpers.requires_numpy()
     def test_issue127(self):
@@ -512,12 +498,11 @@ def test_issue339(self):
         self.assertEqual(q1, q2)
 
     def test_issue354_356_370(self):
-        q = 1 * self.ureg.second / self.ureg.millisecond
         self.assertEqual(
-            "{0:~}".format(1 * self.ureg.second / self.ureg.millisecond), "1.0 s / ms"
+            "{:~}".format(1 * self.ureg.second / self.ureg.millisecond), "1.0 s / ms"
         )
-        self.assertEqual("{0:~}".format(1 * self.ureg.count), "1 count")
-        self.assertEqual("{0:~}".format(1 * self.ureg("MiB")), "1 MiB")
+        self.assertEqual("{:~}".format(1 * self.ureg.count), "1 count")
+        self.assertEqual("{:~}".format(1 * self.ureg("MiB")), "1 MiB")
 
     def test_issue468(self):
         ureg = UnitRegistry()
@@ -546,7 +531,6 @@ def test_issue483(self):
         np.testing.assert_array_equal(p, a ** a)
 
     def test_issue523(self):
-        ureg = UnitRegistry()
         src, dst = UnitsContainer({"meter": 1}), UnitsContainer({"degF": 1})
         value = 10.0
         convert = self.ureg.convert
@@ -635,13 +619,13 @@ def pendulum_period(length, G=Q_(1, "standard_gravity")):
             print(length)
             return (2 * math.pi * (length / G) ** 0.5).to("s")
 
-        l = 1 * ureg.m
+        length = Q_(1, ureg.m)
         # Assume earth gravity
-        t = pendulum_period(l)
+        t = pendulum_period(length)
         self.assertAlmostEqual(t, Q_("2.0064092925890407 second"))
         # Use moon gravity
         moon_gravity = Q_(1.625, "m/s^2")
-        t = pendulum_period(l, moon_gravity)
+        t = pendulum_period(length, moon_gravity)
         self.assertAlmostEqual(t, Q_("4.928936075204336 second"))
 
     def test_issue783(self):
diff --git a/pint/testsuite/test_measurement.py b/pint/testsuite/test_measurement.py
index d37cf6072..ff8cbc881 100644
--- a/pint/testsuite/test_measurement.py
+++ b/pint/testsuite/test_measurement.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 from pint import DimensionalityError
 from pint.testsuite import QuantityTestCase, helpers
 
diff --git a/pint/testsuite/test_numpy.py b/pint/testsuite/test_numpy.py
index b2097bb3d..8fd39d842 100644
--- a/pint/testsuite/test_numpy.py
+++ b/pint/testsuite/test_numpy.py
@@ -1,10 +1,8 @@
-# -*- coding: utf-8 -*-
-
 import copy
 import operator as op
 import unittest
 
-from pint import DimensionalityError, OffsetUnitCalculusError, set_application_registry
+from pint import DimensionalityError, OffsetUnitCalculusError
 from pint.compat import np
 from pint.testsuite import QuantityTestCase, helpers
 from pint.testsuite.test_umath import TestUFuncs
@@ -314,20 +312,20 @@ def test_ediff1d(self):
 
     @helpers.requires_array_function_protocol()
     def test_gradient(self):
-        l = np.gradient([[1, 1], [3, 4]] * self.ureg.m, 1 * self.ureg.J)
+        grad = np.gradient([[1, 1], [3, 4]] * self.ureg.m, 1 * self.ureg.J)
         self.assertQuantityEqual(
-            l[0], [[2.0, 3.0], [2.0, 3.0]] * self.ureg.m / self.ureg.J
+            grad[0], [[2.0, 3.0], [2.0, 3.0]] * self.ureg.m / self.ureg.J
         )
         self.assertQuantityEqual(
-            l[1], [[0.0, 0.0], [1.0, 1.0]] * self.ureg.m / self.ureg.J
+            grad[1], [[0.0, 0.0], [1.0, 1.0]] * self.ureg.m / self.ureg.J
         )
 
-        l = np.gradient(self.Q_([[1, 1], [3, 4]], self.ureg.degC), 1 * self.ureg.J)
+        grad = np.gradient(self.Q_([[1, 1], [3, 4]], self.ureg.degC), 1 * self.ureg.J)
         self.assertQuantityEqual(
-            l[0], [[2.0, 3.0], [2.0, 3.0]] * self.ureg.delta_degC / self.ureg.J
+            grad[0], [[2.0, 3.0], [2.0, 3.0]] * self.ureg.delta_degC / self.ureg.J
         )
         self.assertQuantityEqual(
-            l[1], [[0.0, 0.0], [1.0, 1.0]] * self.ureg.delta_degC / self.ureg.J
+            grad[1], [[0.0, 0.0], [1.0, 1.0]] * self.ureg.delta_degC / self.ureg.J
         )
 
     @helpers.requires_array_function_protocol()
@@ -501,7 +499,7 @@ def test_compress(self):
         )
 
     @helpers.requires_array_function_protocol()
-    def test_compress(self):
+    def test_compress_nep18(self):
         self.assertQuantityEqual(
             np.compress([False, True], self.q, axis=1), [[2], [4]] * self.ureg.m
         )
diff --git a/pint/testsuite/test_numpy_func.py b/pint/testsuite/test_numpy_func.py
index 573f6a462..59f0a2c13 100644
--- a/pint/testsuite/test_numpy_func.py
+++ b/pint/testsuite/test_numpy_func.py
@@ -1,21 +1,18 @@
-# -*- coding: utf-8 -*-
+from unittest.mock import patch
 
 import pint.numpy_func
-
 from pint import DimensionalityError, OffsetUnitCalculusError
 from pint.compat import np
-from pint.testsuite.test_numpy import TestNumpyMethods
 from pint.numpy_func import (
     _is_quantity,
     _is_quantity_sequence,
-    _get_first_input_units,
     convert_to_consistent_units,
-    unwrap_and_wrap_consistent_units,
     get_op_output_unit,
     implements,
     numpy_wrap,
+    unwrap_and_wrap_consistent_units,
 )
-from unittest.mock import patch
+from pint.testsuite.test_numpy import TestNumpyMethods
 
 
 class TestNumPyFuncUtils(TestNumpyMethods):
diff --git a/pint/testsuite/test_pint_eval.py b/pint/testsuite/test_pint_eval.py
index 0dd782970..20f9b46da 100644
--- a/pint/testsuite/test_pint_eval.py
+++ b/pint/testsuite/test_pint_eval.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 import unittest
 
 from pint.compat import tokenizer
diff --git a/pint/testsuite/test_pitheorem.py b/pint/testsuite/test_pitheorem.py
index ed6806398..40abd8c2e 100644
--- a/pint/testsuite/test_pitheorem.py
+++ b/pint/testsuite/test_pitheorem.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 import itertools
 
 from pint import pi_theorem
diff --git a/pint/testsuite/test_quantity.py b/pint/testsuite/test_quantity.py
index 3433cade5..f54e59f3b 100644
--- a/pint/testsuite/test_quantity.py
+++ b/pint/testsuite/test_quantity.py
@@ -1,17 +1,15 @@
-# -*- coding: utf-8 -*-
-
 import copy
 import datetime
 import math
 import operator as op
 import warnings
+from unittest.mock import patch
 
 from pint import DimensionalityError, OffsetUnitCalculusError, UnitRegistry
-from pint.unit import UnitsContainer
 from pint.compat import BehaviorChangeWarning, np
 from pint.testsuite import QuantityTestCase, helpers
 from pint.testsuite.parameterized import ParameterizedTestCase
-from unittest.mock import patch
+from pint.unit import UnitsContainer
 
 
 class TestQuantity(QuantityTestCase):
@@ -144,7 +142,7 @@ def test_quantity_format(self):
 
         # Check the special case that prevents e.g. '3 1 / second'
         x = self.Q_(3, UnitsContainer(second=-1))
-        self.assertEqual("{0}".format(x), "3 / second")
+        self.assertEqual(f"{x}", "3 / second")
 
     @helpers.requires_numpy()
     def test_quantity_array_format(self):
@@ -189,9 +187,9 @@ def test_format_compact(self):
         self.assertEqual(q3.magnitude, q3b.magnitude)
         self.assertEqual(q3.units, q3b.units)
 
-        self.assertEqual("{0:#.1f}".format(q1), "{0}".format(q1b))
-        self.assertEqual("{0:#.1f}".format(q2), "{0}".format(q2b))
-        self.assertEqual("{0:#.1f}".format(q3), "{0}".format(q3b))
+        self.assertEqual(f"{q1:#.1f}", f"{q1b}")
+        self.assertEqual(f"{q2:#.1f}", f"{q2b}")
+        self.assertEqual(f"{q3:#.1f}", f"{q3b}")
 
     def test_default_formatting(self):
         ureg = UnitRegistry()
@@ -271,22 +269,24 @@ def test_to_base_units(self):
         )
 
     def test_convert(self):
-        x = self.Q_("2*inch")
-        self.assertQuantityAlmostEqual(x.to("meter"), self.Q_(2.0 * 0.0254, "meter"))
-        x = self.Q_("2*meter")
-        self.assertQuantityAlmostEqual(x.to("inch"), self.Q_(2.0 / 0.0254, "inch"))
-        x = self.Q_("2*sidereal_second")
-        self.assertQuantityAlmostEqual(x.to("second"), self.Q_(1.994539133, "second"))
-        x = self.Q_("2.54*centimeter/second")
-        self.assertQuantityAlmostEqual(x.to("inch/second"), self.Q_(1, "inch/second"))
-        x = self.Q_("2.54*centimeter")
-        self.assertQuantityAlmostEqual(x.to("inch").magnitude, 1)
         self.assertQuantityAlmostEqual(
-            self.Q_(2, "second").to("millisecond").magnitude, 2000
+            self.Q_("2 inch").to("meter"), self.Q_(2.0 * 0.0254, "meter")
         )
+        self.assertQuantityAlmostEqual(
+            self.Q_("2 meter").to("inch"), self.Q_(2.0 / 0.0254, "inch")
+        )
+        self.assertQuantityAlmostEqual(
+            self.Q_("2 sidereal_year").to("second"), self.Q_(63116297.5325, "second")
+        )
+        self.assertQuantityAlmostEqual(
+            self.Q_("2.54 centimeter/second").to("inch/second"),
+            self.Q_("1 inch/second"),
+        )
+        self.assertAlmostEqual(self.Q_("2.54 centimeter").to("inch").magnitude, 1)
+        self.assertAlmostEqual(self.Q_("2 second").to("millisecond").magnitude, 2000)
 
     @helpers.requires_numpy()
-    def test_convert(self):
+    def test_convert_numpy(self):
 
         # Conversions with single units take a different codepath than
         # Conversions with more than one unit.
@@ -606,7 +606,7 @@ def _test_inplace(self, operator, value1, value2, expected_result, unit=None):
         if isinstance(expected_result, str):
             expected_result = self.Q_(expected_result)
 
-        if not unit is None:
+        if unit is not None:
             value1 = value1 * unit
             value2 = value2 * unit
             expected_result = expected_result * unit
@@ -630,7 +630,7 @@ def _test_not_inplace(self, operator, value1, value2, expected_result, unit=None
         if isinstance(expected_result, str):
             expected_result = self.Q_(expected_result)
 
-        if not unit is None:
+        if unit is not None:
             value1 = value1 * unit
             value2 = value2 * unit
             expected_result = expected_result * unit
diff --git a/pint/testsuite/test_systems.py b/pint/testsuite/test_systems.py
index bff359b1a..008d299f5 100644
--- a/pint/testsuite/test_systems.py
+++ b/pint/testsuite/test_systems.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 from pint import UnitRegistry
 from pint.testsuite import QuantityTestCase
 
@@ -67,9 +65,7 @@ def test_using1(self):
         lines = ["@group mygroup using group1", "meter", "second"]
 
         ureg, root = self._build_empty_reg_root()
-        d = ureg._groups
-
-        g = ureg.Group("group1")
+        ureg.Group("group1")
         grp = ureg.Group.from_lines(lines, lambda x: None)
         self.assertEqual(grp.name, "mygroup")
         self.assertEqual(grp._unit_names, {"meter", "second"})
@@ -80,8 +76,6 @@ def test_using2(self):
         lines = ["@group mygroup using group1,group2", "meter", "second"]
 
         ureg, root = self._build_empty_reg_root()
-        d = ureg._groups
-
         ureg.Group("group1")
         ureg.Group("group2")
         grp = ureg.Group.from_lines(lines, lambda x: None)
@@ -94,8 +88,6 @@ def test_spaces(self):
         lines = ["@group   mygroup   using   group1 , group2", " meter ", " second  "]
 
         ureg, root = self._build_empty_reg_root()
-        d = ureg._groups
-
         ureg.Group("group1")
         ureg.Group("group2")
         grp = ureg.Group.from_lines(lines, lambda x: None)
@@ -108,9 +100,7 @@ def test_invalidate_members(self):
         lines = ["@group mygroup using group1", "meter", "second"]
 
         ureg, root = self._build_empty_reg_root()
-        d = ureg._groups
-
-        g1 = ureg.Group("group1")
+        ureg.Group("group1")
         grp = ureg.Group.from_lines(lines, lambda x: None)
         self.assertIs(root._computed_members, None)
         self.assertIs(grp._computed_members, None)
@@ -138,20 +128,16 @@ def define(ud):
             defs.append(ud.name)
 
         ureg, root = self._build_empty_reg_root()
-        d = ureg._groups
-
-        grp = ureg.Group.from_lines(lines, define)
+        ureg.Group.from_lines(lines, define)
 
         self.assertEqual(["kings_leg", "kings_head"], defs)
 
     def test_members_including(self):
-
         ureg, root = self._build_empty_reg_root()
-        d = ureg._groups
 
         g1 = ureg.Group("group1")
-
         g1.add_units("second", "inch")
+
         g2 = ureg.Group("group2")
         g2.add_units("second", "newton")
 
@@ -185,8 +171,6 @@ def test_implicit_root(self):
         lines = ["@system mks", "meter", "kilogram", "second"]
 
         ureg, root = self._build_empty_reg_root()
-        d = ureg._groups
-
         s = ureg.System.from_lines(lines, lambda x: x)
         s._used_groups = {"root"}
 
@@ -194,8 +178,6 @@ def test_simple_using(self):
         lines = ["@system mks using g1", "meter", "kilogram", "second"]
 
         ureg, root = self._build_empty_reg_root()
-        d = ureg._groups
-
         s = ureg.System.from_lines(lines, lambda x: x)
         s._used_groups = {"root", "g1"}
 
@@ -203,8 +185,6 @@ def test_members_group(self):
         lines = ["@system mk", "meter", "kilogram"]
 
         ureg, root = self._build_empty_reg_root()
-        d = ureg._groups
-
         root.add_units("second")
         s = ureg.System.from_lines(lines, lambda x: x)
         self.assertEqual(s.members, frozenset(["second"]))
@@ -221,13 +201,12 @@ def test_get_compatible_units(self):
 
         lines = ["@system %s using test-imperial" % sysname, "inch"]
 
-        s = ureg.System.from_lines(lines, lambda x: x)
+        ureg.System.from_lines(lines, lambda x: x)
         c = ureg.get_compatible_units("meter", sysname)
         self.assertEqual(c, frozenset([ureg.inch, ureg.yard]))
 
     def test_get_base_units(self):
         sysname = "mysys2"
-
         ureg = UnitRegistry()
 
         g = ureg.get_group("test-imperial")
@@ -249,12 +228,11 @@ def test_get_base_units(self):
 
     def test_get_base_units_different_exponent(self):
         sysname = "mysys3"
-
         ureg = UnitRegistry()
 
         g = ureg.get_group("test-imperial")
         g.add_units("inch", "yard", "pint")
-        c = ureg.get_compatible_units("meter", "test-imperial")
+        ureg.get_compatible_units("meter", "test-imperial")
 
         lines = ["@system %s using test-imperial" % sysname, "pint:meter"]
 
@@ -280,7 +258,6 @@ def test_get_base_units_different_exponent(self):
 
     def test_get_base_units_relation(self):
         sysname = "mysys4"
-
         ureg = UnitRegistry()
 
         g = ureg.get_group("test-imperial")
@@ -302,4 +279,4 @@ def test_get_base_units_relation(self):
     def test_members_nowarning(self):
         ureg = self.ureg
         for name in dir(ureg.sys):
-            s = dir(getattr(ureg.sys, name))
+            dir(getattr(ureg.sys, name))
diff --git a/pint/testsuite/test_umath.py b/pint/testsuite/test_umath.py
index 7b917ae88..a1accc3ac 100644
--- a/pint/testsuite/test_umath.py
+++ b/pint/testsuite/test_umath.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 from pint import DimensionalityError
 from pint.compat import np
 from pint.testsuite import QuantityTestCase, helpers
@@ -442,7 +440,6 @@ def test_arcsin(self):
         )
 
     def test_arccos(self):
-        x = np.arange(0, 0.9, 0.1) * self.ureg.m
         self._test1(
             np.arccos,
             (
diff --git a/pint/testsuite/test_unit.py b/pint/testsuite/test_unit.py
index e1bcf57e5..16b8929d3 100644
--- a/pint/testsuite/test_unit.py
+++ b/pint/testsuite/test_unit.py
@@ -1,21 +1,19 @@
-# -*- coding: utf-8 -*-
-
 import copy
 import functools
 import math
 import re
 
-from pint.compat import np
-from pint.registry import UnitRegistry, LazyRegistry
 from pint import (
     DefinitionSyntaxError,
     DimensionalityError,
     RedefinitionError,
     UndefinedUnitError,
 )
+from pint.compat import np
+from pint.registry import LazyRegistry, UnitRegistry
 from pint.testsuite import QuantityTestCase, helpers
 from pint.testsuite.parameterized import ParameterizedTestCase
-from pint.util import UnitsContainer, ParserHelper
+from pint.util import ParserHelper, UnitsContainer
 
 
 class TestUnit(QuantityTestCase):
@@ -84,12 +82,12 @@ def test_unit_formatting_snake_case(self):
         for spec, result in (
             ("L", r"\mathrm{oil\_barrel}"),
             ("P", "oil_barrel"),
-            ("H", "oil\_barrel"),
+            ("H", r"oil\_barrel"),
             ("C", "oil_barrel"),
             ("~", "oil_bbl"),
             ("L~", r"\mathrm{oil\_bbl}"),
             ("P~", "oil_bbl"),
-            ("H~", "oil\_bbl"),
+            ("H~", r"oil\_bbl"),
             ("C~", "oil_bbl"),
         ):
             with self.subTest(spec):
@@ -212,7 +210,7 @@ def test_base(self):
         ureg.define("meter = [length]")
         self.assertRaises(DefinitionSyntaxError, ureg.define, "meter = [length]")
         self.assertRaises(TypeError, ureg.define, list())
-        x = ureg.define("degC = kelvin; offset: 273.15")
+        ureg.define("degC = kelvin; offset: 273.15")
 
     def test_define(self):
         ureg = UnitRegistry(None)
@@ -234,10 +232,10 @@ def test_load(self):
     def test_default_format(self):
         ureg = UnitRegistry()
         q = ureg.meter
-        s1 = "{0}".format(q)
-        s2 = "{0:~}".format(q)
+        s1 = f"{q}"
+        s2 = f"{q:~}"
         ureg.default_format = "~"
-        s3 = "{0}".format(q)
+        s3 = f"{q}"
         self.assertEqual(s2, s3)
         self.assertNotEqual(s1, s3)
         self.assertEqual(ureg.default_format, "~")
@@ -272,7 +270,6 @@ def test_parse_prefix(self):
             self.ureg.parse_expression("kilometer"),
             self.Q_(1, UnitsContainer(kilometer=1.0)),
         )
-        # self.assertEqual(self.ureg._units['kilometer'], self.Q_(1000., UnitsContainer(meter=1.)))
 
     def test_parse_complex(self):
         self.assertEqual(
@@ -427,11 +424,8 @@ def test_imperial_symbol(self):
         self.assertEqual(self.ureg.get_symbol("international_inch"), "in")
 
     def test_pint(self):
-        p = self.ureg.pint
-        l = self.ureg.liter
-        ip = self.ureg.imperial_pint
-        self.assertLess(p, l)
-        self.assertLess(p, ip)
+        self.assertLess(self.ureg.pint, self.ureg.liter)
+        self.assertLess(self.ureg.pint, self.ureg.imperial_pint)
 
     def test_wraps(self):
         def func(x):
@@ -742,7 +736,7 @@ def test_lazy(self):
         x.test = "test"
         self.assertIsInstance(x, UnitRegistry)
         y = LazyRegistry()
-        q = y("meter")
+        y("meter")
         self.assertIsInstance(y, UnitRegistry)
 
     def test_redefinition(self):
diff --git a/pint/testsuite/test_util.py b/pint/testsuite/test_util.py
index 2d2ccd12e..d27a4ebe2 100644
--- a/pint/testsuite/test_util.py
+++ b/pint/testsuite/test_util.py
@@ -1,22 +1,21 @@
-# -*- coding: utf-8 -*-
-
 import collections
 import copy
 import operator as op
 from decimal import Decimal
+
 from pint.testsuite import BaseTestCase, QuantityTestCase
 from pint.util import (
-    string_preprocessor,
-    find_shortest_path,
-    matrix_to_string,
-    transpose,
-    tokenizer,
-    find_connected_nodes,
     ParserHelper,
     UnitsContainer,
-    to_units_container,
+    find_connected_nodes,
+    find_shortest_path,
     iterable,
+    matrix_to_string,
     sized,
+    string_preprocessor,
+    to_units_container,
+    tokenizer,
+    transpose,
 )
 
 
@@ -207,7 +206,7 @@ def test_eval_token(self):
 
 class TestStringProcessor(BaseTestCase):
     def _test(self, bef, aft):
-        for pattern in ("{0}", "+{0}+"):
+        for pattern in ("{}", "+{}+"):
             b = pattern.format(bef)
             a = pattern.format(aft)
             self.assertEqual(string_preprocessor(b), a)
@@ -309,7 +308,7 @@ def test_matrix_to_string(self):
                 [[1, 2], [3, 4]],
                 row_headers=None,
                 col_headers=None,
-                fmtfun=lambda x: "{0:.2f}".format(x),
+                fmtfun=lambda x: f"{x:.2f}",
             ),
             "1.00\t2.00\n" "3.00\t4.00",
         )
diff --git a/pint/unit.py b/pint/unit.py
index f96e549ff..c64f96694 100644
--- a/pint/unit.py
+++ b/pint/unit.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.unit
     ~~~~~~~~~
@@ -14,11 +13,10 @@
 import operator
 from numbers import Number
 
-from .util import PrettyIPython, UnitsContainer, SharedRegistryObject
-
 from .compat import NUMERIC_TYPES
-from .formatting import siunitx_format_unit
 from .definitions import UnitDefinition
+from .formatting import siunitx_format_unit
+from .util import PrettyIPython, SharedRegistryObject, UnitsContainer
 
 
 class Unit(PrettyIPython, SharedRegistryObject):
diff --git a/pint/util.py b/pint/util.py
index d20778e22..3b6c4672b 100644
--- a/pint/util.py
+++ b/pint/util.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     pint.util
     ~~~~~~~~~
@@ -10,20 +9,20 @@
 """
 
 import logging
-from logging import NullHandler
 import operator
 import re
 from collections.abc import Mapping
 from decimal import Decimal
-from numbers import Number
 from fractions import Fraction
 from functools import lru_cache
+from logging import NullHandler
+from numbers import Number
 from token import NAME, NUMBER
 
-from .compat import tokenizer, NUMERIC_TYPES
+from .compat import NUMERIC_TYPES, tokenizer
+from .errors import DefinitionSyntaxError
 from .formatting import format_unit
 from .pint_eval import build_eval_tree
-from .errors import DefinitionSyntaxError
 
 logger = logging.getLogger(__name__)
 logger.addHandler(NullHandler())
@@ -82,8 +81,10 @@ def column_echelon_form(matrix, ntype=Fraction, transpose_result=False):
         new_M.append(r)
     M = new_M
 
-    #    M = [[ntype(x) for x in row] for row in M]
-    I = [[ntype(1) if n == nc else ntype(0) for nc in range(rows)] for n in range(rows)]
+    # M = [[ntype(x) for x in row] for row in M]
+    I = [  # noqa: E741
+        [ntype(1) if n == nc else ntype(0) for nc in range(rows)] for n in range(rows)
+    ]
     swapped = []
 
     for r in range(rows):
@@ -215,7 +216,7 @@ def find_shortest_path(graph, start, end, path=None):
     path = (path or []) + [start]
     if start == end:
         return path
-    if not start in graph:
+    if start not in graph:
         return None
     shortest = None
     for node in graph[start]:
@@ -228,7 +229,7 @@ def find_shortest_path(graph, start, end, path=None):
 
 
 def find_connected_nodes(graph, start, visited=None):
-    if not start in graph:
+    if start not in graph:
         return None
 
     visited = visited or set()
diff --git a/setup.cfg b/setup.cfg
index 6499fe786..b2de1ede9 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -5,3 +5,27 @@ ignore =
 [bdist_wheel]
 universal = 1
 
+
+[flake8]
+ignore=
+    # whitespace before ':' - doesn't work well with black
+    E203
+    E402
+    # line too long - let black worry about that
+    E501
+    # do not assign a lambda expression, use a def
+    E731
+    # line break before binary operator
+    W503
+exclude=
+    build
+
+
+[isort]
+default_section=THIRDPARTY
+known_first_party=pint
+multi_line_output=3
+include_trailing_comma=True
+force_grid_wrap=0
+use_parentheses=True
+line_length=88