code: def norm(self):
          
          qr_c = quaternion_conjugate(self._qr)
          qd_c = quaternion_conjugate(self._qd)
  
          qr_norm = np.linalg.norm(quaternion_multiply(self._qr, qr_c))
          qd_norm = np.linalg.norm(quaternion_multiply(self._qr, qd_c) + quaternion_multiply(self._qd, qr_c))
  
          return (qr_norm, qd_norm)
docs: :obj:`tuple` of :obj:`numpy.ndarray`: The normalized vectors for qr and qd, respectively.