float.as_integer_ratio

Return a pair of integers, whose ratio is exactly equal to the original float.

The ratio is in lowest terms and has a positive denominator.  Raise
OverflowError on infinities and a ValueError on NaNs.

>>> (10.0).as_integer_ratio()
(10, 1)
>>> (0.0).as_integer_ratio()
(0, 1)
>>> (-.25).as_integer_ratio()
(-1, 4)