adopt pre-commit

.flake8

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+[flake8]
+# Ignore style and complexity
+# E: style errors
+# W: style warnings
+# C: complexity
+# F401: module imported but unused
+# F403: import *
+# F811: redefinition of unused `name` from line `N`
+# F841: local variable assigned but never used
+# E402: module level import not at top of file
+# I100: Import statements are in the wrong order
+# I101: Imported names are in the wrong order
+ignore = E, C, W, F401, F403, F811, F841, E402, I100, I101, D400
+exclude =
+    .cache,
+    .github,
+    build

.pre-commit-config.yaml

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+repos:
+  - repo: https://github.com/pycqa/isort
+    rev: 5.6.3
+    hooks:
+      - id: isort
+  - repo: https://github.com/psf/black
+    rev: 20.8b1
+    hooks:
+      - id: black
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    rev: v2.2.1
+    hooks:
+      - id: prettier
+  - repo: https://gitlab.com/pycqa/flake8
+    rev: "3.8.4"
+    hooks:
+      - id: flake8
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v3.4.0
+    hooks:
+      - id: end-of-file-fixer
+      - id: check-case-conflict
+      - id: check-executables-have-shebangs
+      - id: requirements-txt-fixer

pyproject.toml

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+[tool.isort]
+profile = "black"
+
+[tool.black]
+skip-string-normalization = true
+target_version = [
+    "py27",
+    "py36",
+    "py37",
+    "py38",
+]