code: def forward(self, x, length):
      return self.emb(x).sum(1) / length.unsqueeze(1).float()
  
imports: import dgl
  import dgl.function
  import dgl.nn.pytorch
  import torch
  import torch.nn
  import torch.nn.functional
label_desc: Use image node_id 2 for calling the BagOfWords obj's underlying member method code with example usage: obj.forward(x, length) and returns: unknown