code: def forward(
      self,
      messages: torch.Tensor,
      message_targets: torch.Tensor,
      num_nodes,
  ):
      pass
  
file_path: ptgnn/ptgnn/neuralmodels/gnn/messagepassing/abstractmessagepassing.py
imports: import torch
  from abc import abstractmethod
  from torch import nn
  from torch_scatter import scatter
  from typing import Dict, List, Tuple
label_desc: Use image node_id 1 for calling the AbstractMessageAggregation obj's underlying member method code with example usage: obj.forward(messages, message_targets, num_nodes) without return types