> I'm with Raymond here; I don't think this change is desirable for the math module, either with or without the leading underscore in the name.

Could you please explain what is wrong in adding a helper function which will help to convert different types of numbers to integer ratio correctly?

Currently you need to write a complex code if you need to convert a general number to integer ratio:

    try:
        as_integer_ratio = x.as_integer_ratio
    except AttributeError:
        n = x.numerator
        d = x.denominator
    else:
        n, d = as_integer_ratio()

(and maybe even more complex if you want to add fast path for int).