code: def forward(self, last_layer, prev_layers, mask):
      # pass an extra last_layer to deal with layer 0 (prev_layers is empty)
      if self.prec is None:
          prec = last_layer
      else:
          prec = self.prec(
              prev_layers[-self.prec.n_candidates :]
          )  # skip first
      out = self.op(prec, mask)
      if self.skipconnect is not None:
          connection = self.skipconnect(
              prev_layers[-self.skipconnect.n_candidates :]
          )
          if connection is not None:
              out += connection
      out = self.bn(out, mask)
      return out
  
file_path: nni/examples/nas/legacy/textnas/model.py
imports: import numpy
  import torch
  import torch.nn
  from nni.nas.pytorch import mutables
  from ops import ConvBN, LinearCombine, AvgPool, MaxPool, RNN, Attention, BatchNorm
  from utils import GlobalMaxPool, GlobalAvgPool
label_desc: Use image node_id 2 for calling the Layer obj's underlying member method code with example usage: obj.forward(last_layer, prev_layers, mask) and returns: out