Note that many other PySequence_* functions support only sequences. For example PySequence_Count(o1, o2) is the equivalent of the Python expression o1 + o2 only if o1 is a sequence. If pass integer objects to PySequence_Count() it will return an error.

I would remove "do not" from the documentation. Or even the whole "For objects that do not provide sequence protocol" since this is implied.