code: def postprocess(fetch_map, output_name):
      fetch_dict = {"res_mean_val": []}
      for val in fetch_map[output_name]:
          val = val.tolist()
          val = np.array(val)
          fetch_dict["res_mean_val"].append(np.mean(val))
      fetch_dict["res_mean_val"] = str(fetch_dict["res_mean_val"])
      return fetch_dict
  
file_path: PaddleSeg/test_tipc/serving_cpp/serving_client.py
imports: import sys
  import base64
  import io
  import argparse
  import numpy
  from PIL import Image
  from paddle_serving_client import Client
label_desc: Use image node_id 4 for calling a global function with example usage: postprocess(fetch_map, output_name) and returns: fetch_dict