pycodestyle is not compatible with `PYTHONOPTIMIZE=2`

[mondeja]

pycodestyle relies on function doctrings to show the linting errors. When you run a program with PYTHONOPTIMIZE=2 environment variable or the -OO option the docstrings are stripped, so the next error is raised:

... (traceback)

  File "/.../site-packages/pydocstyle/checker.py", line 160, in check_source
    partition = this_check.__doc__.partition('.\n')
AttributeError: 'NoneType' object has no attribute 'partition'