the name of the slot of nb_multiply not nb_mul
PySequence_Fast generally returns a list not a tuple (closes #16395)
use imperative
inspect.signautre: Fix functools.partial support. Issue #21117
docs: Document __objclass__. Closes #19281.

Initial patch by Nick Coghlan
docs: Better wording for __objclass__ docs. Issue #19281
Issue #20644: OS X installer build support for documentation build changes
in 3.4.1: assume externally supplied sphinx-build is available in /usr/bin.
Issue #21097: Update Makefile with changed install locations of test directories.
issue #21190: Fix the broken docs download link