code: def forward(self, x, mask):
      x, mask = self.time_mix(x, mask)
      x, mask = self.channel_mix(x, mask)
      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 MixerTTSBlock obj's underlying member method code with example usage: obj.forward(x, mask) and returns: x,  mask