Revision 0b7c313851ca highlights an inconsistency in the test case at the top of the TestPredicates class. After removing isawaitable() in Issue 24400, there are now actually eighteen is* functions. The comment in the test case still says there are sixteen (from before the two iscoroutine* functions were added), and so does the documentation it references: ‘The sixteen functions whose names begin with “is” ’ <https://docs.python.org/3.5/library/inspect.html#types-and-members>. The quick fix is to change all the numbers to eighteen.

But maybe a better fix is to drop it all and rewrite the documentation to just say “The functions whose names begin with “is” are mainly provided . . .”.