def n_members(self):
        """
        Returns the number of members in the domain if it
        `is_finite`, otherwise, returns `None`.

        :type: ``int``
        """
        return int(binom(self.n_meas + self.n_elements -1, self.n_elements - 1))
Returns the number of members in the domain if it
        `is_finite`, otherwise, returns `None`.

        :type: ``int``