I expected return int if I gave x as integer to copysign.

I encounterd two problems.
I'd like to fix this problems.
but I can't come up with nice idea.
therefore I just report for you.

one:
>>> import math
>>> a = [0, 1, 2, 3]
>>> i = 1
>>> i_copysign = math.copysign(i, -1)
>>> a[i_copysign]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: list indices must be integers, not float

two:
>>> n = 10 ** 20
>>> math.copysign(n + 1, 1) == n + 1
False