Summary

pyplot has a number of unused imports. Some of them are intentional e.g. plt.cycler, some seem unnecessary e.g. plt.TickHelper.

Proposed fix

• Go through all unused imports and decide if we want to keep it. Also use github search to help on the decision. We don't want to force lots of users to change their imports.

• Mark all intentional imports with a comment

• Deprecate all unwanted imports.