Doc test errors
- [ ] closes #42907 
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry

Hello @willie3838! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:

* In the file [`pandas/core/groupby/groupby.py`](https://github.com/pandas-dev/pandas/blob/227fc0db6a48d0c6c5c5361b491631d14452b6e3/pandas/core/groupby/groupby.py):

> [Line 321:89](https://github.com/pandas-dev/pandas/blob/227fc0db6a48d0c6c5c5361b491631d14452b6e3/pandas/core/groupby/groupby.py#L321): [E501](https://duckduckgo.com/?q=pep8%20E501) line too long (90 > 88 characters)
> [Line 321:91](https://github.com/pandas-dev/pandas/blob/227fc0db6a48d0c6c5c5361b491631d14452b6e3/pandas/core/groupby/groupby.py#L321): [W291](https://duckduckgo.com/?q=pep8%20W291) trailing whitespace





##### Comment last updated at 2021-08-15 18:52:02 UTC