Currently, math.isnan(n) and math.isinf(n) for n an int may raise OverflowError if n is too big to convert to a float, e.g.:

py> math.isnan(10**10000)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: int too large to convert to float


But this conversion is unnecessary. int does not support either INF or NAN, so there is no need to convert the value to float first. If the argument is an int, the result must be False.

The same applies to Fraction.