class_docstr: This module implements feed-forward network(after the Multi-Head Network) equation:
  FFN(x) = max(0, x @ W_1 + b_1) @ W_2 + b_2
code: def forward(self, x):
      return self.w_2(self.dropout(th.relu(self.w_1(x))))
  
imports: import torch
  import torch.nn
  from torch.nn import LayerNorm
  import copy
label_desc: Use image node_id 2 for calling the PositionwiseFeedForward obj's underlying member method code with example usage: obj.forward(x) and returns: self