code: def _get_frame(self, key):
          
          cached = self.current_key is None
          layout_frame = self.layout.clone(shared_data=False)
          if key == self.current_key and not self._force:
              return self.current_frame
          else:
              self.current_key = key
  
          key_map = dict(zip([d.name for d in self.dimensions], key))
          for path, item in self.layout.items():
              frame = get_nested_plot_frame(item, key_map, cached)
              if frame is not None:
                  layout_frame[path] = frame
          traverse_setter(self, '_force', False)
  
          self.current_frame = layout_frame
          return layout_frame
docs: Creates a clone of the Layout with the nth-frame for each
          Element.