DOC: updates documentations Closes #21749

[salomondush]

• xref DOCS: Update import statements in docstrings #21749
• tests added / passed
• Ensure all linting tests pass, see here for how to run them
• whatsnew entry

[pep8speaks]

Hello @salomondush! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2021-08-16 18:33:32 UTC

[jreback]

all of these should use the standard conventions (except for the internal uses of network)

[jreback]

great does this close all of the items in the original issue?

[salomondush]

I only changed those in the directory ./pandas/util/testing.py. Others have remained the same.

[jreback]

thanks @salomondush happy to have a PR on other items in the original issue as well