code: def remove_neighbours(self):
          
          # Get the HEALPix cells of the MOC at its max depth
          ipix = self._best_res_pixels()
  
          hp = HEALPix(nside=(1 << self.max_order), order='nested')
          # Extend it to include the max depth neighbor cells.
          extend_ipix = AbstractMOC._neighbour_pixels(hp, ipix)
  
          # Get only the max depth HEALPix cells lying at the border of the MOC
          neigh_ipix = np.setxor1d(extend_ipix, ipix)
  
          # Remove these pixels from ``ipix``
          border_ipix = AbstractMOC._neighbour_pixels(hp, neigh_ipix)
          reduced_ipix = np.setdiff1d(ipix, border_ipix)
  
          # Build the reduced MOC, i.e. MOC without its pixels which were located at its border.
          shift = 2 * (AbstractMOC.HPY_MAX_NORDER - self.max_order)
          reduced_itv = np.vstack((reduced_ipix << shift, (reduced_ipix + 1) << shift)).T
          self._interval_set = IntervalSet(reduced_itv)
          return self
docs: Removes from the MOC instance the HEALPix cells located at its border.
  
          The depth of the HEALPix cells removed is equal to the maximum depth of the MOC instance.
  
          Returns
          -------
          moc : `~mocpy.moc.MOC`
              self minus its HEALPix cells located at its border.