code: def forward(self, mixture):
      mixture = torch.unsqueeze(mixture, 1)
      mixture_w = self.nonlinear(self.conv(mixture))
      return mixture_w
  
imports: import math
  from collections import OrderedDict
  from typing import Dict, List, Optional, Tuple
  import torch
  import torch.nn
  import torch.nn.functional
  from espnet2.enh.layers.dpmulcat import DPMulCat
  from espnet2.enh.layers.dprnn import merge_feature, split_feature
  from espnet2.enh.separator.abs_separator import AbsSeparator
label_desc: Use image node_id 2 for calling the Encoder obj's underlying member method code with example usage: obj.forward(mixture) and returns: mixture_w