Equality test with tolerance
        (same orientation, not necessarily same rotation)


        :param other: a QuaternionBase
        :returns: true if the quaternions are almost equal

def close(self, other):
        """
        Equality test with tolerance
        (same orientation, not necessarily same rotation)


        :param other: a QuaternionBase
        :returns: true if the quaternions are almost equal
        """
        if isinstance(other, QuaternionBase):
            return np.allclose(self.q, other.q) or np.allclose(self.q, -other.q)
        return NotImplemented