Thanks! I will also attach all `flake8`'s output if someone is going to need it:

```
» flake8 --select=F811 Lib/test
Lib/test/test_descr.py:1165:13: F811 redefinition of unused 'C' from line 1158
Lib/test/test_descr.py:1172:13: F811 redefinition of unused 'C' from line 1165
Lib/test/test_descr.py:1179:13: F811 redefinition of unused 'C' from line 1172
Lib/test/test_descr.py:1186:13: F811 redefinition of unused 'C' from line 1179
Lib/test/test_descr.py:1192:9: F811 redefinition of unused 'C' from line 1186
Lib/test/test_descr.py:1198:9: F811 redefinition of unused 'C' from line 1192
Lib/test/test_descr.py:1488:13: F811 redefinition of unused 'C' from line 1480
Lib/test/test_descr.py:1498:13: F811 redefinition of unused 'C' from line 1488
Lib/test/test_descr.py:1506:13: F811 redefinition of unused 'C' from line 1498
Lib/test/test_descr.py:1514:13: F811 redefinition of unused 'C' from line 1506
Lib/test/test_descr.py:4076:13: F811 redefinition of unused 'X' from line 4073
Lib/test/test_descr.py:4079:13: F811 redefinition of unused 'X' from line 4076
Lib/test/test_descr.py:4084:13: F811 redefinition of unused 'X' from line 4079
Lib/test/test_descr.py:4087:13: F811 redefinition of unused 'X' from line 4084
Lib/test/test_descr.py:4090:9: F811 redefinition of unused 'X' from line 4087
Lib/test/test_buffer.py:759:5: F811 redefinition of unused 'genslices' from line 694
Lib/test/test_buffer.py:760:5: F811 redefinition of unused 'genslices_ndim' from line 698
Lib/test/test_buffer.py:761:5: F811 redefinition of unused 'permutations' from line 20
Lib/test/test_syntax.py:1555:5: F811 redefinition of unused 'test_break_outside_loop' from line 1525
Lib/test/test_typing.py:108:13: F811 redefinition of unused 'A' from line 105
Lib/test/test_typing.py:148:13: F811 redefinition of unused 'A' from line 145
Lib/test/test_typing.py:332:13: F811 redefinition of unused 'C' from line 329
Lib/test/test_typing.py:335:13: F811 redefinition of unused 'C' from line 332
Lib/test/test_typing.py:880:13: F811 redefinition of unused 'P' from line 877
Lib/test/test_typing.py:883:13: F811 redefinition of unused 'P' from line 880
Lib/test/test_typing.py:1385:13: F811 redefinition of unused 'P' from line 1383
Lib/test/test_typing.py:1387:13: F811 redefinition of unused 'P' from line 1385
Lib/test/test_typing.py:1389:13: F811 redefinition of unused 'P' from line 1387
Lib/test/test_typing.py:1665:13: F811 redefinition of unused 'MyGeneric' from line 1663
Lib/test/test_typing.py:2295:13: F811 redefinition of unused 'Subclass' from line 2292
Lib/test/test_typing.py:2478:13: F811 redefinition of unused 'C' from line 2475
Lib/test/test_typing.py:2522:13: F811 redefinition of unused 'C' from line 2519
Lib/test/test_typing.py:4532:5: F811 redefinition of unused 'test_hash_eq' from line 4475
Lib/test/test_typing.py:4652:13: F811 redefinition of unused 'C' from line 4648
Lib/test/test_typing.py:4844:13: F811 redefinition of unused 'C' from line 4841
Lib/test/datetimetester.py:1867:9: F811 redefinition of unused 'io' from line 5
Lib/test/datetimetester.py:3991:9: F811 redefinition of unused 'io' from line 5
Lib/test/test_genericclass.py:101:13: F811 redefinition of unused 'D' from line 95
Lib/test/test_genericclass.py:114:13: F811 redefinition of unused 'D' from line 108
Lib/test/test_subclassinit.py:235:13: F811 redefinition of unused 'MyClass' from line 221
Lib/test/test_subclassinit.py:246:9: F811 redefinition of unused 'MyClass' from line 235
Lib/test/test_subclassinit.py:268:9: F811 redefinition of unused 'MyClass' from line 259
Lib/test/test_tabnanny.py:7:1: F811 redefinition of unused 'mock' from line 6
Lib/test/test_compile.py:1178:5: F811 redefinition of unused 'test_func_args' from line 1171
Lib/test/test_dataclasses.py:517:13: F811 redefinition of unused 'A' from line 512
Lib/test/test_dataclasses.py:527:13: F811 redefinition of unused 'A' from line 517
Lib/test/test_dataclasses.py:681:21: F811 redefinition of unused 'Point' from line 672
Lib/test/test_dataclasses.py:692:21: F811 redefinition of unused 'Point' from line 681
Lib/test/test_dataclasses.py:702:17: F811 redefinition of unused 'C' from line 697
Lib/test/test_dataclasses.py:1840:9: F811 redefinition of unused 'C' from line 1834
Lib/test/test_dataclasses.py:2387:13: F811 redefinition of unused 'C' from line 2378
Lib/test/test_dataclasses.py:2396:13: F811 redefinition of unused 'C' from line 2387
Lib/test/test_dataclasses.py:2405:13: F811 redefinition of unused 'C' from line 2396
Lib/test/test_dataclasses.py:2778:13: F811 redefinition of unused 'C' from line 2770
Lib/test/test_dataclasses.py:2784:9: F811 redefinition of unused 'C' from line 2778
Lib/test/test_dataclasses.py:3678:13: F811 redefinition of unused 'A' from line 3673
Lib/test/test_dataclasses.py:3683:13: F811 redefinition of unused 'A' from line 3678
Lib/test/test_dataclasses.py:3825:13: F811 redefinition of unused 'A' from line 3816
Lib/test/test_dataclasses.py:3834:13: F811 redefinition of unused 'A' from line 3825
Lib/test/test_dataclasses.py:3843:9: F811 redefinition of unused 'A' from line 3834
Lib/test/test_dataclasses.py:3851:9: F811 redefinition of unused 'A' from line 3843
Lib/test/test_dataclasses.py:3870:13: F811 redefinition of unused 'B' from line 3857
Lib/test/test_functools.py:566:13: F811 redefinition of unused 'B' from line 563
Lib/test/test_functools.py:569:13: F811 redefinition of unused 'B' from line 566
Lib/test/test_yield_from.py:921:9: F811 redefinition of unused 'two' from line 890
Lib/test/time_hashlib.py:60:5: F811 redefinition of unused 'creatorFunc' from line 9
Lib/test/test_keywordonlyarg.py:173:13: F811 redefinition of unused 'f' from line 169
Lib/test/test_codecs.py:35:5: F811 redefinition of unused 'UINT' from line 35
Lib/test/test_dict.py:1441:5: F811 redefinition of unused 'test_dict_items_result_gc' from line 1429
Lib/test/test_pkg.py:200:9: F811 redefinition of unused 't5' from line 193
Lib/test/test_pty.py:19:1: F811 redefinition of unused 'tty' from line 10
Lib/test/test_enum.py:625:13: F811 redefinition of unused 'Wrong' from line 622
Lib/test/test_enum.py:628:13: F811 redefinition of unused 'Wrong' from line 625
Lib/test/test_enum.py:631:13: F811 redefinition of unused 'Wrong' from line 628
Lib/test/test_enum.py:634:13: F811 redefinition of unused 'Wrong' from line 631
Lib/test/test_enum.py:746:13: F811 redefinition of unused 'Color' from line 739
Lib/test/test_enum.py:754:13: F811 redefinition of unused 'Color' from line 746
Lib/test/test_enum.py:758:17: F811 redefinition of unused 'red' from line 756
Lib/test/test_enum.py:873:5: F811 redefinition of unused 'test_mixin_format_warning' from line 860
Lib/test/test_enum.py:1022:13: F811 redefinition of unused 'Huh' from line 1012
Lib/test/test_enum.py:2106:13: F811 redefinition of unused 'Color' from line 2101
Lib/test/test_enum.py:2603:13: F811 redefinition of unused 'ThirdFailedStrEnum' from line 2599
Lib/test/test_enum.py:2607:13: F811 redefinition of unused 'ThirdFailedStrEnum' from line 2603
Lib/test/test_enum.py:2667:13: F811 redefinition of unused 'ThirdFailedStrEnum' from line 2663
Lib/test/test_enum.py:2671:13: F811 redefinition of unused 'ThirdFailedStrEnum' from line 2667
Lib/test/test_enum.py:2729:13: F811 redefinition of unused 'ThirdFailedStrEnum' from line 2725
Lib/test/test_enum.py:2733:13: F811 redefinition of unused 'ThirdFailedStrEnum' from line 2729
Lib/test/test_enum.py:4168:1: F811 redefinition of unused 'TestHelpers' from line 107
Lib/test/test_import/__init__.py:277:13: F811 redefinition of unused 'x' from line 272
Lib/test/test_zoneinfo/test_zoneinfo.py:1096:9: F811 redefinition of unused '_add' from line 1068
Lib/test/test_zoneinfo/test_zoneinfo.py:1120:9: F811 redefinition of unused '_add' from line 1096
Lib/test/test_zoneinfo/test_zoneinfo.py:1145:9: F811 redefinition of unused '_add' from line 1120
Lib/test/test_zoneinfo/test_zoneinfo.py:1169:9: F811 redefinition of unused '_add' from line 1145
Lib/test/test_zoneinfo/test_zoneinfo.py:1182:9: F811 redefinition of unused '_add' from line 1169
Lib/test/test_zoneinfo/test_zoneinfo.py:1195:9: F811 redefinition of unused '_add' from line 1182
Lib/test/test_zoneinfo/test_zoneinfo.py:1216:9: F811 redefinition of unused '_add' from line 1195
Lib/test/test_zoneinfo/test_zoneinfo.py:1249:9: F811 redefinition of unused '_add' from line 1216
Lib/test/test_zoneinfo/test_zoneinfo.py:1272:9: F811 redefinition of unused '_add' from line 1249
Lib/test/support/__init__.py:1392:9: F811 redefinition of unused '_platform_specific' from line 1388
Lib/test/test_email/test__header_value_parser.py:398:5: F811 redefinition of unused 'test_get_unstructured_invalid_ew' from line 304
Lib/test/test_asyncio/test_sslproto.py:18:1: F811 redefinition of unused 'support' from line 5
```

I will refactor some more in my existing PR.
Thanks a lot, Éric!