code: def forward(
      self,
      feat,
      out_enc,
      label=None,
      valid_ratios=None,
      word_positions=None,
      train_mode=True,
  ):
      self.train_mode = train_mode
  
      if train_mode:
          return self.forward_train(
              feat, out_enc, label, valid_ratios, word_positions
          )
      return self.forward_test(
          feat, out_enc, valid_ratios, word_positions
      )
  
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, valid_ratios, word_positions, train_mode) and returns: self, self