code: def build_graph(self, left, right, gt_flow):
      x = self.preprocess(left, right)
      prediction = self.graph_structure(x)
      prediction = self.postprocess(prediction)
      tf.identity(prediction, name="prediction")
      # endpoint error
      tf.reduce_mean(tf.norm(prediction - gt_flow, axis=1), name="epe")
  
imports: import tensorflow
  from tensorpack import ModelDesc, argscope, enable_argscope_for_module
label_desc: Use image node_id 6 for calling the FlowNetBase obj's underlying member method code with example usage: obj.build_graph(left, right, gt_flow) without return types