PR 3211 - LGTM, but is not CLA signed.

Elena, a couple of notes on your patch. Using :ref:`regular expression object <re-objects>` to link to the section of the documentation is preferred, as it does not rely on a consistent URL. Also, be mindful of line lengths, feel free to break lines to avoid this. If you would like to submit a PR on Github for these changes, it can more easily be merged in. (Check https://docs.python.org/devguide/pullrequest.html for more info).