':param max_denominator: Integer, the maximum denominator value
:returns: Tuple of (numerator, denominator)'

def limit_rational(self, max_denominator):

    if (self.denominator == 0):
        return (self.numerator, self.denominator)
    f = self._val.limit_denominator(max_denominator)
    return (f.numerator, f.denominator)
