code: def forward_test(self, feat, out_enc, img_metas):
      raise NotImplementedError
  
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 3 for calling the BaseDecoder obj's underlying member method code with example usage: obj.forward_test(feat, out_enc, img_metas) without return types