add pre-commit

.pre-commit-config.yaml

@@ -0,0 +1,27 @@
+repos:
+- repo: https://github.com/pre-commit/pre-commit-hooks
+  rev: v3.3.0
+  hooks:
+  - id: trailing-whitespace
+  - id: end-of-file-fixer
+  - id: check-docstring-first
+  - id: check-yaml
+  - id: debug-statements
+  - id: check-ast
+- repo: https://github.com/ambv/black
+  rev: 20.8b1
+  hooks:
+  - id: black
+- repo: https://github.com/asottile/pyupgrade
+  rev: v2.7.3
+  hooks:
+  - id: pyupgrade
+    args: ['--py36-plus']
+- repo: https://github.com/timothycrosley/isort
+  rev: 5.6.4
+  hooks:
+  - id: isort
+- repo: https://gitlab.com/pycqa/flake8
+  rev: 3.8.4
+  hooks:
+  - id: flake8

setup.cfg

@@ -0,0 +1,14 @@
+[flake8]
+max-line-length = 100
+ignore = E501, W503, E203, E266
+max-complexity = 18
+select = B, C, E, F, W, T4, B9
+exclude = .git, .tox, __pycache__, dist
+
+[isort]
+profile = black
+
+[mypy]
+strict_optional = True
+disallow_untyped_calls = True
+ignore_missing_imports = True