class_docstr: Example GNN layer.
code: def forward(self, batch):
      x, edge_index = batch.x, batch.edge_index
      x = torch.matmul(x, self.weight)
  
      batch.x = self.propagate(edge_index, x=x)
  
      return batch
  
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 3 for calling the ExampleConv1 obj's underlying member method code with example usage: obj.forward(batch) and returns: batch