Some remaining questions:
Please let me know if there is anything else you'd like me to change. Thanks!
This is mostly a copy of AcceptLanguage.__contains__. Changes: - It calls ._old_match() instead of ._match(). - It returns False instead of None when no matches found. - Additional documentation and pending-deprecation warning. - Tests changed to use @pytest.mark.parametrize.
A class returns True for .__nonzero__/.__bool__ by default, but we write a method so we can document it and have a consistent interface across the three AcceptLanguage classes.