Initial patch contributed by Edmond Burnett.

Revise module docstring and update itertools import and use.

urllib.parse.unquote() and urllib.parse.unquote_to_bytes().

urllib.parse.unquote() and urllib.parse.unquote_to_bytes().

urllib.parse.unquote() and urllib.parse.unquote_to_bytes().

If PYTHON is undefined, this fails without the launcher (installed with 3.3 or
from PyPI), but this is better than always failing. Patch from Zachary Ware.

__loader__ is not set on a module. This brings the exception in line
with when __loader__ is None (which is equivalent to not having the
attribute defined).

automatically used by import.

into sys.path_importer_cache.

set __loader__ on a module when set to None.

Thanks to Gökcen Eraslan for the fix.