This directory contains some stub files for 3rdparty modules, which don't have any.
Copied from the .deb package, which isn't in the search path from the virtual env.
The PyQt5 package, when installed with pip, does not include the stub files, which
are created when building PyQt5 from source. These files are just copied from a manual
Also tweaked the files a bit, because they don't work with mypy as is...
Manually crafted, with just the subset of class that I actually use (i.e. incomplete).