code: def get_dynamical_matrix_at_q(self, q):
          
  
          self._set_dynamical_matrix()
          if self._dynamical_matrix is None:
              msg = ("Dynamical matrix has not yet built.")
              raise RuntimeError(msg)
  
          self._dynamical_matrix.set_dynamical_matrix(q)
          return self._dynamical_matrix.get_dynamical_matrix()
docs: Calculate dynamical matrix at a given q-point
  
          Parameters
          ----------
          q: array_like
              A q-vector.
              shape=(3,), dtype='double'
  
          Returns
          -------
          dynamical_matrix: ndarray
              Dynamical matrix.
              shape=(bands, bands), dtype='complex'