code: def forward(self, x, mask):
      new_x, mask = self.fn(self.norm(x), mask)
      x = x + new_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 PreNormResidual obj's underlying member method code with example usage: obj.forward(x, mask) and returns: x,  mask