[Python-ideas] divmod(): fallback to __floordiv__ and __mod__?

Currently, calling divmod() on a class with __floordiv__ and __mod__ defined, but not __divmod__ raises a TypeError. Is there any reason why it doesn't fallback to (self // x, self % x)? The invariants described in the function documentation should still apply (with well behaved % and //). If divmod() doesn't make sense setting it to None should be permitted. - Spencer