code: def get_layers(self):
          
          layers = set()
          for element in self.elements:
              if isinstance(element, PolygonSet):
                  layers.update(element.layers)
              elif isinstance(element, CellReference) or isinstance(
                      element, CellArray):
                  layers.update(element.ref_cell.get_layers())
          for label in self.labels:
              layers.add(label.layer)
          return layers
docs: Returns a set of layers in this cell.
  
          Returns
          -------
          out : set
              Set of the layers used in this cell.