cmp: Replacement for built-in function cmp that was removed in Python 3
As part of the move away from cmp-style comparisons, the cmp() function was removed in Python 3.
If it is necessary (usually to conform to an external API), you can provide it with this code:
def cmp(x, y):
Replacement for built-in function cmp that was removed in Python 3
Compare the two objects x and y and return an integer according to
the outcome. The return value is negative if x < y, zero if x == y
and strictly positive if x > y.
return (x > y) - (x < y)