code: def oslicer(self, tile):
          
          mask = None
          vecs = tile.coords(form='meshed')
          for v in vecs:
              v[self.slicer] = -1
              mask = mask & (v > 0) if mask is not None else (v>0)
          return tuple(np.array(i).astype('int') for i in zip(*[v[mask] for v in vecs]))
docs: Opposite slicer, the outer part wrt to a field