class_docstr: The bond encoder used in OGB molecule dataset.
  
  Args:
      emb_dim (int): The output embedding dimension.
  
  Example:
      >>> encoder = BondEncoder(emb_dim=16)
      >>> batch = torch.randint(0, 10, (10, 3))
      >>> encoder(batch).size()
      torch.Size([10, 16])
code: def forward(self, batch):
      bond_embedding = 0
      for i in range(batch.edge_attr.shape[1]):
          edge_attr = batch.edge_attr
          bond_embedding += self.bond_embedding_list[i](edge_attr[:, i])
  
      batch.edge_attr = bond_embedding
      return batch
  
file_path: pytorch_geometric/torch_geometric/graphgym/models/encoder.py
imports: import torch
  from torch_geometric.graphgym.register import register_edge_encoder, register_node_encoder
label_desc: Use image node_id 2 for calling the BondEncoder obj's underlying member method code with example usage: obj.forward(batch) and returns: batch