code: def forward(
      self, feat, out_enc, label=None, img_metas=None, train_mode=True
  ):
      self.train_mode = train_mode
  
      if train_mode:
          return self.forward_train(feat, out_enc, label, img_metas)
      return self.forward_test(feat, out_enc, img_metas)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import math
  import paddle
  from paddle import ParamAttr
  import paddle.nn
  import paddle.nn.functional
label_desc: Use image node_id 4 for calling the BaseDecoder obj's underlying member method code with example usage: obj.forward(feat, out_enc, label, img_metas, train_mode) and returns: self, self