I think that none of these API calls can fail, but only few of them are
documented as such. Add the sentence "This function always succeeds" (which is
the same already used e.g. by PyNumber_Check) to all of them.
(cherry picked from commit 315fc52db1)
Co-authored-by: Antonio Cuni <anto.cuni@gmail.com>
Co-authored-by: Antonio Cuni <anto.cuni@gmail.com>