code: def block_sep1(self, Y):
          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).
          shp = Y.shape[0:self.cri.axisC] + self.y1shp[self.cri.axisC:]
          return Y[(slice(None),)*self.cri.axisC +
                   (slice(self.y0I, None),)].reshape(shp)
docs: r"""Separate variable into component corresponding to
          :math:`\mathbf{y}_1` in :math:`\mathbf{y}\;\;`.