code: def _dcm_to_q(self, dcm):
          
          assert(isinstance(dcm, Matrix3))
          arr = self._matrix3_to_dcm_array(dcm)
          return super(Quaternion, self)._dcm_to_q(arr)
docs: Create q from dcm (Matrix3)
          :param dcm: Matrix3
          :returns: array q which represents a quaternion [w, x, y, z]