diff --git a/slither/core/variables/__init__.py b/slither/core/variables/__init__.py
index 638f0f3a4e..53872853aa 100644
--- a/slither/core/variables/__init__.py
+++ b/slither/core/variables/__init__.py
@@ -1,2 +1,8 @@
 from .state_variable import StateVariable
 from .variable import Variable
+from .local_variable_init_from_tuple import LocalVariableInitFromTuple
+from .local_variable import LocalVariable
+from .top_level_variable import TopLevelVariable
+from .event_variable import EventVariable
+from .function_type_variable import FunctionTypeVariable
+from .structure_variable import StructureVariable
diff --git a/slither/printers/summary/ck.py b/slither/printers/summary/ck.py
index f7a8510391..78da23756b 100644
--- a/slither/printers/summary/ck.py
+++ b/slither/printers/summary/ck.py
@@ -32,6 +32,7 @@
 """
 from slither.printers.abstract_printer import AbstractPrinter
 from slither.utils.ck import CKMetrics
+from slither.utils.output import Output
 
 
 class CK(AbstractPrinter):
@@ -40,7 +41,7 @@ class CK(AbstractPrinter):
 
     WIKI = "https://github.com/trailofbits/slither/wiki/Printer-documentation#ck"
 
-    def output(self, _filename):
+    def output(self, _filename: str) -> Output:
         if len(self.contracts) == 0:
             return self.generate_output("No contract found")
 
diff --git a/slither/printers/summary/halstead.py b/slither/printers/summary/halstead.py
index 8144e467f7..d3c3557db9 100644
--- a/slither/printers/summary/halstead.py
+++ b/slither/printers/summary/halstead.py
@@ -25,6 +25,7 @@
 """
 from slither.printers.abstract_printer import AbstractPrinter
 from slither.utils.halstead import HalsteadMetrics
+from slither.utils.output import Output
 
 
 class Halstead(AbstractPrinter):
@@ -33,7 +34,7 @@ class Halstead(AbstractPrinter):
 
     WIKI = "https://github.com/trailofbits/slither/wiki/Printer-documentation#halstead"
 
-    def output(self, _filename):
+    def output(self, _filename: str) -> Output:
         if len(self.contracts) == 0:
             return self.generate_output("No contract found")
 
diff --git a/slither/printers/summary/martin.py b/slither/printers/summary/martin.py
index c49e63fcb5..a0f1bbfcb1 100644
--- a/slither/printers/summary/martin.py
+++ b/slither/printers/summary/martin.py
@@ -11,6 +11,7 @@
 """
 from slither.printers.abstract_printer import AbstractPrinter
 from slither.utils.martin import MartinMetrics
+from slither.utils.output import Output
 
 
 class Martin(AbstractPrinter):
@@ -19,7 +20,7 @@ class Martin(AbstractPrinter):
 
     WIKI = "https://github.com/trailofbits/slither/wiki/Printer-documentation#martin"
 
-    def output(self, _filename):
+    def output(self, _filename: str) -> Output:
         if len(self.contracts) == 0:
             return self.generate_output("No contract found")
 
diff --git a/slither/utils/ck.py b/slither/utils/ck.py
index 7b0d1afd90..ffba663ad2 100644
--- a/slither/utils/ck.py
+++ b/slither/utils/ck.py
@@ -110,7 +110,7 @@ class CKContractMetrics:
     dit: int = 0
     cbo: int = 0
 
-    def __post_init__(self):
+    def __post_init__(self) -> None:
         if not hasattr(self.contract, "functions"):
             return
         self.count_variables()
@@ -123,7 +123,7 @@ def __post_init__(self):
 
     # pylint: disable=too-many-locals
     # pylint: disable=too-many-branches
-    def calculate_metrics(self):
+    def calculate_metrics(self) -> None:
         """Calculate the metrics for a contract"""
         rfc = self.public  # initialize with public getter count
         for func in self.contract.functions:
@@ -186,7 +186,7 @@ def calculate_metrics(self):
             self.ext_calls += len(external_calls)
             self.rfc = rfc
 
-    def count_variables(self):
+    def count_variables(self) -> None:
         """Count the number of variables in a contract"""
         state_variable_count = 0
         constant_count = 0
@@ -302,7 +302,7 @@ class CKMetrics:
         ("Core", "core", CORE_KEYS),
     )
 
-    def __post_init__(self):
+    def __post_init__(self) -> None:
         martin_metrics = MartinMetrics(self.contracts).contract_metrics
         dependents = {
             inherited.name: {
@@ -323,6 +323,7 @@ def __post_init__(self):
             for contract in self.contracts
         }
 
+        subtitle = ""
         # Update each section
         for (title, attr, keys) in self.SECTIONS:
             if attr == "core":
diff --git a/slither/utils/encoding.py b/slither/utils/encoding.py
new file mode 100644
index 0000000000..288b581505
--- /dev/null
+++ b/slither/utils/encoding.py
@@ -0,0 +1,202 @@
+from typing import Union
+
+from slither.core import variables
+from slither.core.declarations import (
+    SolidityVariable,
+    SolidityVariableComposed,
+    Structure,
+    Enum,
+    Contract,
+)
+from slither.core import solidity_types
+from slither.slithir import operations
+from slither.slithir import variables as SlitherIRVariable
+
+
+# pylint: disable=too-many-branches
+def ntype(_type: Union[solidity_types.Type, str]) -> str:
+    if isinstance(_type, solidity_types.ElementaryType):
+        _type = str(_type)
+    elif isinstance(_type, solidity_types.ArrayType):
+        if isinstance(_type.type, solidity_types.ElementaryType):
+            _type = str(_type)
+        else:
+            _type = "user_defined_array"
+    elif isinstance(_type, Structure):
+        _type = str(_type)
+    elif isinstance(_type, Enum):
+        _type = str(_type)
+    elif isinstance(_type, solidity_types.MappingType):
+        _type = str(_type)
+    elif isinstance(_type, solidity_types.UserDefinedType):
+        if isinstance(_type.type, Contract):
+            _type = f"contract({_type.type.name})"
+        elif isinstance(_type.type, Structure):
+            _type = f"struct({_type.type.name})"
+        elif isinstance(_type.type, Enum):
+            _type = f"enum({_type.type.name})"
+    else:
+        _type = str(_type)
+
+    _type = _type.replace(" memory", "")
+    _type = _type.replace(" storage ref", "")
+
+    if "struct" in _type:
+        return "struct"
+    if "enum" in _type:
+        return "enum"
+    if "tuple" in _type:
+        return "tuple"
+    if "contract" in _type:
+        return "contract"
+    if "mapping" in _type:
+        return "mapping"
+    return _type.replace(" ", "_")
+
+
+# pylint: disable=too-many-branches
+def encode_var_for_compare(var: Union[variables.Variable, SolidityVariable]) -> str:
+
+    # variables
+    if isinstance(var, SlitherIRVariable.Constant):
+        return f"constant({ntype(var.type)},{var.value})"
+    if isinstance(var, SolidityVariableComposed):
+        return f"solidity_variable_composed({var.name})"
+    if isinstance(var, SolidityVariable):
+        return f"solidity_variable{var.name}"
+    if isinstance(var, SlitherIRVariable.TemporaryVariable):
+        return "temporary_variable"
+    if isinstance(var, SlitherIRVariable.ReferenceVariable):
+        return f"reference({ntype(var.type)})"
+    if isinstance(var, variables.LocalVariable):
+        return f"local_solc_variable({ntype(var.type)},{var.location})"
+    if isinstance(var, variables.StateVariable):
+        if not (var.is_constant or var.is_immutable):
+            try:
+                slot, _ = var.contract.compilation_unit.storage_layout_of(var.contract, var)
+            except KeyError:
+                slot = var.name
+        else:
+            slot = var.name
+        return f"state_solc_variable({ntype(var.type)},{slot})"
+    if isinstance(var, variables.LocalVariableInitFromTuple):
+        return "local_variable_init_tuple"
+    if isinstance(var, SlitherIRVariable.TupleVariable):
+        return "tuple_variable"
+
+    # default
+    return ""
+
+
+# pylint: disable=too-many-branches
+def encode_ir_for_upgradeability_compare(ir: operations.Operation) -> str:
+    # operations
+    if isinstance(ir, operations.Assignment):
+        return f"({encode_var_for_compare(ir.lvalue)}):=({encode_var_for_compare(ir.rvalue)})"
+    if isinstance(ir, operations.Index):
+        return f"index({ntype(ir.variable_right.type)})"
+    if isinstance(ir, operations.Member):
+        return "member"  # .format(ntype(ir._type))
+    if isinstance(ir, operations.Length):
+        return "length"
+    if isinstance(ir, operations.Binary):
+        return f"binary({encode_var_for_compare(ir.variable_left)}{ir.type}{encode_var_for_compare(ir.variable_right)})"
+    if isinstance(ir, operations.Unary):
+        return f"unary({str(ir.type)})"
+    if isinstance(ir, operations.Condition):
+        return f"condition({encode_var_for_compare(ir.value)})"
+    if isinstance(ir, operations.NewStructure):
+        return "new_structure"
+    if isinstance(ir, operations.NewContract):
+        return "new_contract"
+    if isinstance(ir, operations.NewArray):
+        return f"new_array({ntype(ir.array_type)})"
+    if isinstance(ir, operations.NewElementaryType):
+        return f"new_elementary({ntype(ir.type)})"
+    if isinstance(ir, operations.Delete):
+        return f"delete({encode_var_for_compare(ir.lvalue)},{encode_var_for_compare(ir.variable)})"
+    if isinstance(ir, operations.SolidityCall):
+        return f"solidity_call({ir.function.full_name})"
+    if isinstance(ir, operations.InternalCall):
+        return f"internal_call({ntype(ir.type_call)})"
+    if isinstance(ir, operations.EventCall):  # is this useful?
+        return "event"
+    if isinstance(ir, operations.LibraryCall):
+        return "library_call"
+    if isinstance(ir, operations.InternalDynamicCall):
+        return "internal_dynamic_call"
+    if isinstance(ir, operations.HighLevelCall):  # TODO: improve
+        return "high_level_call"
+    if isinstance(ir, operations.LowLevelCall):  # TODO: improve
+        return "low_level_call"
+    if isinstance(ir, operations.TypeConversion):
+        return f"type_conversion({ntype(ir.type)})"
+    if isinstance(ir, operations.Return):  # this can be improved using values
+        return "return"  # .format(ntype(ir.type))
+    if isinstance(ir, operations.Transfer):
+        return f"transfer({encode_var_for_compare(ir.call_value)})"
+    if isinstance(ir, operations.Send):
+        return f"send({encode_var_for_compare(ir.call_value)})"
+    if isinstance(ir, operations.Unpack):  # TODO: improve
+        return "unpack"
+    if isinstance(ir, operations.InitArray):  # TODO: improve
+        return "init_array"
+
+    # default
+    return ""
+
+
+def encode_ir_for_halstead(ir: operations.Operation) -> str:
+    # operations
+    if isinstance(ir, operations.Assignment):
+        return "assignment"
+    if isinstance(ir, operations.Index):
+        return "index"
+    if isinstance(ir, operations.Member):
+        return "member"  # .format(ntype(ir._type))
+    if isinstance(ir, operations.Length):
+        return "length"
+    if isinstance(ir, operations.Binary):
+        return f"binary({str(ir.type)})"
+    if isinstance(ir, operations.Unary):
+        return f"unary({str(ir.type)})"
+    if isinstance(ir, operations.Condition):
+        return f"condition({encode_var_for_compare(ir.value)})"
+    if isinstance(ir, operations.NewStructure):
+        return "new_structure"
+    if isinstance(ir, operations.NewContract):
+        return "new_contract"
+    if isinstance(ir, operations.NewArray):
+        return f"new_array({ntype(ir.array_type)})"
+    if isinstance(ir, operations.NewElementaryType):
+        return f"new_elementary({ntype(ir.type)})"
+    if isinstance(ir, operations.Delete):
+        return "delete"
+    if isinstance(ir, operations.SolidityCall):
+        return f"solidity_call({ir.function.full_name})"
+    if isinstance(ir, operations.InternalCall):
+        return f"internal_call({ntype(ir.type_call)})"
+    if isinstance(ir, operations.EventCall):  # is this useful?
+        return "event"
+    if isinstance(ir, operations.LibraryCall):
+        return "library_call"
+    if isinstance(ir, operations.InternalDynamicCall):
+        return "internal_dynamic_call"
+    if isinstance(ir, operations.HighLevelCall):  # TODO: improve
+        return "high_level_call"
+    if isinstance(ir, operations.LowLevelCall):  # TODO: improve
+        return "low_level_call"
+    if isinstance(ir, operations.TypeConversion):
+        return f"type_conversion({ntype(ir.type)})"
+    if isinstance(ir, operations.Return):  # this can be improved using values
+        return "return"  # .format(ntype(ir.type))
+    if isinstance(ir, operations.Transfer):
+        return "transfer"
+    if isinstance(ir, operations.Send):
+        return "send"
+    if isinstance(ir, operations.Unpack):  # TODO: improve
+        return "unpack"
+    if isinstance(ir, operations.InitArray):  # TODO: improve
+        return "init_array"
+    # default
+    raise NotImplementedError(f"encode_ir_for_halstead: {ir}")
diff --git a/slither/utils/halstead.py b/slither/utils/halstead.py
index 64dd1f6a1a..9ec952e486 100644
--- a/slither/utils/halstead.py
+++ b/slither/utils/halstead.py
@@ -25,13 +25,17 @@
 
 """
 import math
+from collections import OrderedDict
 from dataclasses import dataclass, field
 from typing import Tuple, List, Dict
-from collections import OrderedDict
+
 from slither.core.declarations import Contract
 from slither.slithir.variables.temporary import TemporaryVariable
+from slither.utils.encoding import encode_ir_for_halstead
 from slither.utils.myprettytable import make_pretty_table, MyPrettyTable
-from slither.utils.upgradeability import encode_ir_for_halstead
+
+
+# pylint: disable=too-many-branches
 
 
 @dataclass
@@ -55,7 +59,7 @@ class HalsteadContractMetrics:
     T: float = 0
     B: float = 0
 
-    def __post_init__(self):
+    def __post_init__(self) -> None:
         """Operators and operands can be passed in as constructor args to avoid computing
         them based on the contract. Useful for computing metrics for ALL_CONTRACTS"""
 
@@ -85,7 +89,7 @@ def to_dict(self) -> Dict[str, float]:
             }
         )
 
-    def populate_operators_and_operands(self):
+    def populate_operators_and_operands(self) -> None:
         """Populate the operators and operands lists."""
         operators = []
         operands = []
@@ -104,7 +108,7 @@ def populate_operators_and_operands(self):
         self.all_operators.extend(operators)
         self.all_operands.extend(operands)
 
-    def compute_metrics(self, all_operators=None, all_operands=None):
+    def compute_metrics(self, all_operators=None, all_operands=None) -> None:
         """Compute the Halstead metrics."""
         if all_operators is None:
             all_operators = self.all_operators
@@ -183,17 +187,17 @@ class HalsteadMetrics:
         ("Extended 2/2", "extended2", EXTENDED2_KEYS),
     )
 
-    def __post_init__(self):
+    def __post_init__(self) -> None:
         # Compute the metrics for each contract and for all contracts.
         self.update_contract_metrics()
         self.add_all_contracts_metrics()
         self.update_reporting_sections()
 
-    def update_contract_metrics(self):
+    def update_contract_metrics(self) -> None:
         for contract in self.contracts:
             self.contract_metrics[contract.name] = HalsteadContractMetrics(contract=contract)
 
-    def add_all_contracts_metrics(self):
+    def add_all_contracts_metrics(self) -> None:
         # If there are more than 1 contract, compute the metrics for all contracts.
         if len(self.contracts) <= 1:
             return
@@ -211,7 +215,7 @@ def add_all_contracts_metrics(self):
             None, all_operators=all_operators, all_operands=all_operands
         )
 
-    def update_reporting_sections(self):
+    def update_reporting_sections(self) -> None:
         # Create the table and text for each section.
         data = {
             contract.name: self.contract_metrics[contract.name].to_dict()
diff --git a/slither/utils/martin.py b/slither/utils/martin.py
index fb62a4c584..c336227fd2 100644
--- a/slither/utils/martin.py
+++ b/slither/utils/martin.py
@@ -26,12 +26,12 @@ class MartinContractMetrics:
     i: float = 0.0
     d: float = 0.0
 
-    def __post_init__(self):
+    def __post_init__(self) -> None:
         if self.ce + self.ca > 0:
             self.i = float(self.ce / (self.ce + self.ca))
             self.d = float(abs(self.i - self.abstractness))
 
-    def to_dict(self):
+    def to_dict(self) -> Dict:
         return {
             "Dependents": self.ca,
             "Dependencies": self.ce,
@@ -65,12 +65,12 @@ class MartinMetrics:
     )
     SECTIONS: Tuple[Tuple[str, str, Tuple[str]]] = (("Core", "core", CORE_KEYS),)
 
-    def __post_init__(self):
+    def __post_init__(self) -> None:
         self.update_abstractness()
         self.update_coupling()
         self.update_reporting_sections()
 
-    def update_reporting_sections(self):
+    def update_reporting_sections(self) -> None:
         # Create the table and text for each section.
         data = {
             contract.name: self.contract_metrics[contract.name].to_dict()
@@ -98,7 +98,7 @@ def update_reporting_sections(self):
                 SectionInfo(title=section_title, pretty_table=pretty_table, txt=txt),
             )
 
-    def update_abstractness(self) -> float:
+    def update_abstractness(self) -> None:
         abstract_contract_count = 0
         for c in self.contracts:
             if not c.is_fully_implemented:
@@ -106,7 +106,7 @@ def update_abstractness(self) -> float:
         self.abstractness = float(abstract_contract_count / len(self.contracts))
 
     # pylint: disable=too-many-branches
-    def update_coupling(self) -> Dict:
+    def update_coupling(self) -> None:
         dependencies = {}
         for contract in self.contracts:
             external_calls = []
diff --git a/slither/utils/upgradeability.py b/slither/utils/upgradeability.py
index 5cc3dba08c..bbb253175e 100644
--- a/slither/utils/upgradeability.py
+++ b/slither/utils/upgradeability.py
@@ -1,66 +1,28 @@
-from typing import Optional, Tuple, List, Union
+from typing import Optional, Tuple, List
+
+from slither.analyses.data_dependency.data_dependency import get_dependencies
+from slither.core.cfg.node import Node, NodeType
 from slither.core.declarations import (
     Contract,
-    Structure,
-    Enum,
-    SolidityVariableComposed,
-    SolidityVariable,
     Function,
 )
-from slither.core.solidity_types import (
-    Type,
-    ElementaryType,
-    ArrayType,
-    MappingType,
-    UserDefinedType,
-)
-from slither.core.variables.local_variable import LocalVariable
-from slither.core.variables.local_variable_init_from_tuple import LocalVariableInitFromTuple
-from slither.core.variables.state_variable import StateVariable
-from slither.analyses.data_dependency.data_dependency import get_dependencies
-from slither.core.variables.variable import Variable
 from slither.core.expressions import (
     Literal,
     Identifier,
     CallExpression,
     AssignmentOperation,
 )
-from slither.core.cfg.node import Node, NodeType
+from slither.core.solidity_types import (
+    ElementaryType,
+)
+from slither.core.variables.local_variable import LocalVariable
+from slither.core.variables.state_variable import StateVariable
+from slither.core.variables.variable import Variable
 from slither.slithir.operations import (
-    Operation,
-    Assignment,
-    Index,
-    Member,
-    Length,
-    Binary,
-    Unary,
-    Condition,
-    NewArray,
-    NewStructure,
-    NewContract,
-    NewElementaryType,
-    SolidityCall,
-    Delete,
-    EventCall,
-    LibraryCall,
-    InternalDynamicCall,
-    HighLevelCall,
     LowLevelCall,
-    TypeConversion,
-    Return,
-    Transfer,
-    Send,
-    Unpack,
-    InitArray,
-    InternalCall,
-)
-from slither.slithir.variables import (
-    TemporaryVariable,
-    TupleVariable,
-    Constant,
-    ReferenceVariable,
 )
 from slither.tools.read_storage.read_storage import SlotInfo, SlitherReadStorage
+from slither.utils.encoding import encode_ir_for_upgradeability_compare
 
 
 class TaintedExternalContract:
@@ -385,201 +347,13 @@ def is_function_modified(f1: Function, f2: Function) -> bool:
         if len(node_f1.irs) != len(node_f2.irs):
             return True
         for i, ir in enumerate(node_f1.irs):
-            if encode_ir_for_compare(ir) != encode_ir_for_compare(node_f2.irs[i]):
+            if encode_ir_for_upgradeability_compare(ir) != encode_ir_for_upgradeability_compare(
+                node_f2.irs[i]
+            ):
                 return True
     return False
 
 
-# pylint: disable=too-many-branches
-def ntype(_type: Union[Type, str]) -> str:
-    if isinstance(_type, ElementaryType):
-        _type = str(_type)
-    elif isinstance(_type, ArrayType):
-        if isinstance(_type.type, ElementaryType):
-            _type = str(_type)
-        else:
-            _type = "user_defined_array"
-    elif isinstance(_type, Structure):
-        _type = str(_type)
-    elif isinstance(_type, Enum):
-        _type = str(_type)
-    elif isinstance(_type, MappingType):
-        _type = str(_type)
-    elif isinstance(_type, UserDefinedType):
-        if isinstance(_type.type, Contract):
-            _type = f"contract({_type.type.name})"
-        elif isinstance(_type.type, Structure):
-            _type = f"struct({_type.type.name})"
-        elif isinstance(_type.type, Enum):
-            _type = f"enum({_type.type.name})"
-    else:
-        _type = str(_type)
-
-    _type = _type.replace(" memory", "")
-    _type = _type.replace(" storage ref", "")
-
-    if "struct" in _type:
-        return "struct"
-    if "enum" in _type:
-        return "enum"
-    if "tuple" in _type:
-        return "tuple"
-    if "contract" in _type:
-        return "contract"
-    if "mapping" in _type:
-        return "mapping"
-    return _type.replace(" ", "_")
-
-
-# pylint: disable=too-many-branches
-def encode_ir_for_compare(ir: Operation) -> str:
-    # operations
-    if isinstance(ir, Assignment):
-        return f"({encode_var_for_compare(ir.lvalue)}):=({encode_var_for_compare(ir.rvalue)})"
-    if isinstance(ir, Index):
-        return f"index({ntype(ir.variable_right.type)})"
-    if isinstance(ir, Member):
-        return "member"  # .format(ntype(ir._type))
-    if isinstance(ir, Length):
-        return "length"
-    if isinstance(ir, Binary):
-        return f"binary({encode_var_for_compare(ir.variable_left)}{ir.type}{encode_var_for_compare(ir.variable_right)})"
-    if isinstance(ir, Unary):
-        return f"unary({str(ir.type)})"
-    if isinstance(ir, Condition):
-        return f"condition({encode_var_for_compare(ir.value)})"
-    if isinstance(ir, NewStructure):
-        return "new_structure"
-    if isinstance(ir, NewContract):
-        return "new_contract"
-    if isinstance(ir, NewArray):
-        return f"new_array({ntype(ir.array_type)})"
-    if isinstance(ir, NewElementaryType):
-        return f"new_elementary({ntype(ir.type)})"
-    if isinstance(ir, Delete):
-        return f"delete({encode_var_for_compare(ir.lvalue)},{encode_var_for_compare(ir.variable)})"
-    if isinstance(ir, SolidityCall):
-        return f"solidity_call({ir.function.full_name})"
-    if isinstance(ir, InternalCall):
-        return f"internal_call({ntype(ir.type_call)})"
-    if isinstance(ir, EventCall):  # is this useful?
-        return "event"
-    if isinstance(ir, LibraryCall):
-        return "library_call"
-    if isinstance(ir, InternalDynamicCall):
-        return "internal_dynamic_call"
-    if isinstance(ir, HighLevelCall):  # TODO: improve
-        return "high_level_call"
-    if isinstance(ir, LowLevelCall):  # TODO: improve
-        return "low_level_call"
-    if isinstance(ir, TypeConversion):
-        return f"type_conversion({ntype(ir.type)})"
-    if isinstance(ir, Return):  # this can be improved using values
-        return "return"  # .format(ntype(ir.type))
-    if isinstance(ir, Transfer):
-        return f"transfer({encode_var_for_compare(ir.call_value)})"
-    if isinstance(ir, Send):
-        return f"send({encode_var_for_compare(ir.call_value)})"
-    if isinstance(ir, Unpack):  # TODO: improve
-        return "unpack"
-    if isinstance(ir, InitArray):  # TODO: improve
-        return "init_array"
-
-    # default
-    return ""
-
-
-# pylint: disable=too-many-branches
-def encode_ir_for_halstead(ir: Operation) -> str:
-    # operations
-    if isinstance(ir, Assignment):
-        return "assignment"
-    if isinstance(ir, Index):
-        return "index"
-    if isinstance(ir, Member):
-        return "member"  # .format(ntype(ir._type))
-    if isinstance(ir, Length):
-        return "length"
-    if isinstance(ir, Binary):
-        return f"binary({str(ir.type)})"
-    if isinstance(ir, Unary):
-        return f"unary({str(ir.type)})"
-    if isinstance(ir, Condition):
-        return f"condition({encode_var_for_compare(ir.value)})"
-    if isinstance(ir, NewStructure):
-        return "new_structure"
-    if isinstance(ir, NewContract):
-        return "new_contract"
-    if isinstance(ir, NewArray):
-        return f"new_array({ntype(ir.array_type)})"
-    if isinstance(ir, NewElementaryType):
-        return f"new_elementary({ntype(ir.type)})"
-    if isinstance(ir, Delete):
-        return "delete"
-    if isinstance(ir, SolidityCall):
-        return f"solidity_call({ir.function.full_name})"
-    if isinstance(ir, InternalCall):
-        return f"internal_call({ntype(ir.type_call)})"
-    if isinstance(ir, EventCall):  # is this useful?
-        return "event"
-    if isinstance(ir, LibraryCall):
-        return "library_call"
-    if isinstance(ir, InternalDynamicCall):
-        return "internal_dynamic_call"
-    if isinstance(ir, HighLevelCall):  # TODO: improve
-        return "high_level_call"
-    if isinstance(ir, LowLevelCall):  # TODO: improve
-        return "low_level_call"
-    if isinstance(ir, TypeConversion):
-        return f"type_conversion({ntype(ir.type)})"
-    if isinstance(ir, Return):  # this can be improved using values
-        return "return"  # .format(ntype(ir.type))
-    if isinstance(ir, Transfer):
-        return "transfer"
-    if isinstance(ir, Send):
-        return "send"
-    if isinstance(ir, Unpack):  # TODO: improve
-        return "unpack"
-    if isinstance(ir, InitArray):  # TODO: improve
-        return "init_array"
-    # default
-    raise NotImplementedError(f"encode_ir_for_halstead: {ir}")
-
-
-# pylint: disable=too-many-branches
-def encode_var_for_compare(var: Variable) -> str:
-
-    # variables
-    if isinstance(var, Constant):
-        return f"constant({ntype(var.type)},{var.value})"
-    if isinstance(var, SolidityVariableComposed):
-        return f"solidity_variable_composed({var.name})"
-    if isinstance(var, SolidityVariable):
-        return f"solidity_variable{var.name}"
-    if isinstance(var, TemporaryVariable):
-        return "temporary_variable"
-    if isinstance(var, ReferenceVariable):
-        return f"reference({ntype(var.type)})"
-    if isinstance(var, LocalVariable):
-        return f"local_solc_variable({ntype(var.type)},{var.location})"
-    if isinstance(var, StateVariable):
-        if not (var.is_constant or var.is_immutable):
-            try:
-                slot, _ = var.contract.compilation_unit.storage_layout_of(var.contract, var)
-            except KeyError:
-                slot = var.name
-        else:
-            slot = var.name
-        return f"state_solc_variable({ntype(var.type)},{slot})"
-    if isinstance(var, LocalVariableInitFromTuple):
-        return "local_variable_init_tuple"
-    if isinstance(var, TupleVariable):
-        return "tuple_variable"
-
-    # default
-    return ""
-
-
 def get_proxy_implementation_slot(proxy: Contract) -> Optional[SlotInfo]:
     """
     Gets information about the storage slot where a proxy's implementation address is stored.