code: def forward(self, tgt):
      if self.normalize_before:
          return self.forward_pre(tgt)
      return self.forward_post(tgt)
  
imports: import copy
  import math
  from typing import Optional
  import torch
  import torch.nn.functional
  from torch import Tensor, nn
label_desc: Use image node_id 6 for calling the FFNLayer obj's underlying member method code with example usage: obj.forward(tgt) and returns: self, self