It took me a while to track down a bug that stemmed from this -
>>> from datetime import date as dt, time as tm, datetime as dtm
>>> x = dt.today()
>>> isinstance(x, dt)
>>> isinstance(x, dtm)
>>> y = dtm.now()
>>> isinstance(y, dt)
True <--- ??
>>> isinstance(y, dtm)
>>> isinstance(y, tm)
Why is a dtm instance also an instance of dt?
From the docs, "A datetime object is a single object containing all the
information from a date object and a time object."
If it was using multiple inheritance, a dtm should also be an instance
of tm, but it is not.
This is using Python 3.7.2.