Follow-up from "linting source code and tests"
The following discussion from !11 (merged) should be addressed:
@gweather I need to disable pylints member check here because
valid.mechanismmay return to different types: A
It would be a little cleaner to not allow a mechanisms to be built with strike, dip or rake to be
None, woudnt it? From a user perspective I would expect some exception if I create a mechanism from