error: make HintException a mix-in class not derived from BaseException (API)
HintException is unrelated to the hierarchy of errors. It is an implementation
detail whether a class inherits from HintException or not, a sort of "private
inheritance" in C++.
New Hint isn't an exception class, which prevents catching error by its type:
try:
dosomething()
except error.Hint:
pass
Unfortunately, this passes on PyPy 5.3.1, but not on Python 2, and raises more
detailed TypeError on Python 3.
(binary:application/octet-stream)