flake8: copy over poetry configuration

Author: abn

.flake8

@@ -1,19 +1,33 @@
 [flake8]
+min_python_version = 3.7.0
 max-line-length = 88
-ignore = E501, E203, W503
+ban-relative-imports = true
+# flake8-use-fstring: https://github.com/MichaelKim0407/flake8-use-fstring#--percent-greedy-and---format-greedy
+format-greedy = 1
+inline-quotes = double
+# Allow omission of a return type hint for __init__ if at least one argument is annotated
+# used by flake8-annotations
+mypy-init-return = true
+enable-extensions = TC, TC1
+type-checking-exempt-modules = typing, typing-extensions
+eradicate-whitelist-extend = ^-.*;
+extend-ignore =
+    # E203: Whitespace before ':' (pycqa/pycodestyle#373)
+    E203,
+    # SIM106: Handle error-cases first
+    SIM106,
+    # ANN101: Missing type annotation for self in method
+    ANN101,
+    # ANN102: Missing type annotation for cls in classmethod
+    ANN102,
 per-file-ignores =
-    __init__.py:F401
-exclude =
-    .git
-    __pycache__
-    setup.py
-    build
-    dist
-    releases
-    .venv
-    .tox
-    .mypy_cache
-    .pytest_cache
-    .vscode
-    .github
-    tests/fixtures/
+    # F401: Module imported by unused (non-implicit modules)
+    # TC002: Move third-party import '...' into a type-checking block
+    __init__.py:F401,TC002,
+    # ANN201: Missing return type annotation for public function
+    tests/test_*:ANN201
+    tests/**/test_*:ANN201
+extend-exclude =
+    # External to the project's coding standards:
+    tests/fixtures/*,
+    tests/**/fixtures/*,