code: def forward(self, x, mask=None):
      x, mask = self.first_mix_layer(x, mask)
      x = self.act(x)
      x = self.drop_1(x)
      x, mask = self.second_mix_layer(x, mask)
      x = self.drop_2(x)
      return x, mask
  
imports: import math
  import torch
  from torch import nn
  from nemo.collections.tts.modules.submodules import ConvNorm
  from nemo.collections.tts.modules.transformer import PositionalEmbedding
label_desc: Use image node_id 2 for calling the Mix obj's underlying member method code with example usage: obj.forward(x, mask) and returns: x,  mask