def in_base(self, base):
        """
        Return value in ``base``.

        :returns: Radix in ``base``
        :rtype: Radix
        :raises ConvertError: if ``base`` is less than 2
        """
        if base == self.base:
            return copy.deepcopy(self)
        (result, _) = Radices.from_rational(self.as_rational(), base)
        return result