Return pair n, d of integers such that the value of self is
        exactly equal to n/d, n and d are relatively prime, and d >= 1.

def as_integer_ratio(self):
        """Return pair n, d of integers such that the value of self is
        exactly equal to n/d, n and d are relatively prime, and d >= 1.

        """
        if not is_finite(self):
            raise ValueError("Can't express infinity or nan as "
                             "an integer ratio")
        elif not self:
            return 0, 1

        # convert to a hex string, and from there to a fraction
        negative, digits, e = _mpfr_get_str2(
            16,
            0,
            self,
            ROUND_TIES_TO_EVEN,
        )
        digits = digits.rstrip('0')

        # find number of trailing 0 bits in last hex digit
        v = int(digits[-1], 16)
        v &= -v
        n, d = int(digits, 16) // v, 1
        e = (e - len(digits) << 2) + {1: 0, 2: 1, 4: 2, 8: 3}[v]

        # abs(number) now has value n * 2**e, and n is odd
        if e >= 0:
            n <<= e
        else:
            d <<= -e

        return (-n if negative else n), d