Pound keys were interpreted as comments. This is annoying when we want
to parse html color codes, such as in:
$ tutor config save --set "INDIGO_PRIMARY_COLOR=#225522"
$ tutor config printvalue INDIGO_PRIMARY_COLOR
null
Close #866.
Annotations were generated with pyannotate:
https://github.com/dropbox/pyannotate
We are running in strict mode, which is awesome!
This affects a large part of the code base, which might be an issue for
people running a fork of Tutor. Nonetheless, the behavior should not be
affected. If anything, this process has helped find and resolve a few
type-related bugs. Thus, this is not considered as a breaking change.