code: def forward(self, est_source):
      est_source = torch.transpose(est_source, 2, 3)
      est_source = nn.AvgPool2d((1, self.kernel_size))(est_source)
      est_source = overlap_and_add(est_source, self.kernel_size // 2)
  
      return est_source
  
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 Decoder obj's underlying member method code with example usage: obj.forward(est_source) and returns: est_source