class_docstr: Example GNN layer.
code: def message(self, x_j):
      return x_j
  
imports: import torch
  import torch.nn
  from torch.nn import Parameter
  from torch_geometric.graphgym.config import cfg
  from torch_geometric.graphgym.register import register_layer
  from torch_geometric.nn.conv import MessagePassing
  from torch_geometric.nn.inits import glorot, zeros
label_desc: Use image node_id 4 for calling the ExampleConv2Layer obj's underlying member method code with example usage: obj.message(x_j) and returns: x_j