Albert Y. Shih

It can't be "user-provided" because the loopback generation is performed on module import. If we don't approach this with a context manager, the tolerance would need to be developer-defined. This...

> > I'm not sure what a sensible API would be for specifying the tolerance. > > Callback function to evaluate if two frames are the same? Sure, that'd work.

Presumably the user would be missing subpackage (non-optional) dependencies because they typed `pip install sunpy` instead of `pip install sunpy[...]`. So, instead of leaving such a user to play whack-a-mole...

> At the moment if a user does pip install sunpy then e.g. map can be imported without error but then map factory will give mpl errors when used. I'm...

Sure, that would work.

This would then be the line to change: https://github.com/sunpy/sunpy/blob/3189938ac16df5aefc713a424240f4dc54914711/sunpy/map/mapbase.py#L2353

Is this a recent development? In the past, my `api` files would definitely be cached when using `make html`, which I know because I'd have to manually clear it out...

Hmm, okay, maybe `sunpy.coordinates` API files aren't getting invalidated =)

Heh, maybe it's a Mac thing!

Oh, never mind then