code: def __call__(self, graph):
      if graph.a is not None and hasattr(
          self.layer_class, "preprocess"
      ):
          graph.a = self.layer_class.preprocess(graph.a)
  
      return graph
  
label_desc: Use image node_id 2 for calling the LayerPreprocess obj's underlying member method code with example usage: obj.__call__(graph) and returns: graph