code: def block_cat(self, Y0, Y1):
          r
  
          # This method is overridden because we have to change the
          # mechanism for combining the Y0 and Y1 blocks into a single
          # array (see comment in the __init__ method).
          y0shp = Y0.shape[0:self.cri.axisC] + (-1,)
          y1shp = Y1.shape[0:self.cri.axisC] + (-1,)
          return np.concatenate((Y0.reshape(y0shp),
                                 Y1.reshape(y1shp)), axis=self.cri.axisC)
docs: r"""Concatenate components corresponding to :math:`\mathbf{y}_0`
          and :math:`\mathbf{y}_1` to form :math:`\mathbf{y}\;\;`.