[Feature] Flake8' tool to perform additional formatting and semantic checking of code.

[mozga-intel]

Description

There is used flake8' tool to perform additional formatting and semantic checking of code. This pull request contains a pre-commit git hook, a requirement file, .flake8 file with a flake8 configuration. (Related to: #20406, #20356)

1. Since Flake8 needs to be installed with an appropriate configuration, the file with the requirements has to be run:

pip install -r requirements-flake8.txt

2. After that, we need to set up a symbolic link to a given file: To create a symbolic link to a given file, open your terminal and type:

ln -s ../../tools/git-pre-commit .git/hooks/pre-commit

3. If you have not set up the pre-commit hooks, you can run it locally in your local branch.

Future consideration

1. Flake8 tool should be run also on a CI.
2. *.py files need to be adjusted firstly. Flake8 check the entire file.
3. Add a pre-commit configuration: [pre-commit manager]
   3.1: Create a file named .pre-commit -config.yaml.
   3.2: Set up the full set of options for a given file.

Checklist

Essentials

• PR's title starts with a category (e.g. [BUGFIX], [MODEL], [TUTORIAL], [FEATURE], [DOC], etc)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage
• Code is well-documented

Changes

• Feature1, tests, (and when applicable, API doc)
• Feature2, tests, (and when applicable, API doc)

Comments

• If this change is a backward incompatible change, why must this change be made.
• Interesting edge cases to note here

[mxnet-bot]

Hey @mozga-intel , Thanks for submitting the PR
All tests are already queued to run once. If tests fail, you can trigger one or more tests again with the following commands:

• To trigger all jobs: @mxnet-bot run ci [all]
• To trigger specific jobs: @mxnet-bot run ci [job1, job2]

---

CI supported jobs: [windows-gpu, unix-cpu, unix-gpu, website, clang, windows-cpu, centos-gpu, edge, centos-cpu, sanity, miscellaneous]

---

Note:
Only following 3 categories can trigger CI :PR Author, MXNet Committer, Jenkins Admin.
All CI tests must pass before the PR can be merged.

[mozga-intel]

@mxnet-bot run ci [unix-gpu]

[mxnet-bot]

Jenkins CI successfully triggered : [unix-gpu]

[mxnet-bot]

Jenkins CI successfully triggered : [sanity]

[mozga-intel]

@mxnet-bot run ci [all]

[mxnet-bot]

Jenkins CI successfully triggered : [miscellaneous, centos-gpu, windows-cpu, unix-cpu, sanity, edge, windows-gpu, website, centos-cpu, unix-gpu, clang]

[mozga-intel]

Following the pull-request description, running flake8 on the current master produces a bunch of errors (pasted below). At some point of time, some checking has not been enabled yet. Please have a look at the log below:

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:54:31: E231 missing whitespace after ','

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:54:34: E225 missing whitespace around operator

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:64:27: E231 missing whitespace after ','

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:64:31: E231 missing whitespace after ','

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:64:34: E225 missing whitespace around operator

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:70:12: F632 use ==/!= to compare constant literals (str, bytes, int, float, tuple)

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:73:40: C416 Unnecessary list comprehension - rewrite using list().

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:78:24: E231 missing whitespace after ','

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:78:26: E231 missing whitespace after ','

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:78:29: E231 missing whitespace after ','

[2021-08-04T10:47:16.901Z] ./tests/python/gpu/test_numpy_fallback.py:78:32: E231 missing whitespace after ','

To pass sanity-check, adjusting those ones to the flake8' report is needed.

[mozga-intel]

Close this PR as it is flake8 is replaced by #20684