Here's the essence of a patch.

Suppose the input is Python integers, and the output is a mathematical integer. In this case we can make the output a Python integer by using the helper function

>>> def wibble(p, q):
...     if type(p) == type(q) == int and p%q == 0:
...         return p // q
...     else:
...         return p / q
... 
>>> wibble(4, 2)
2
>>> wibble(3, 2)
1.5

This will also work for average.