code: def init_op(self):
      self.preprocess_pipeline = Compose(GLOBAL_VAR["preprocess_ops"])
  
imports: import copy
  from paddle_serving_server.web_service import WebService, Op
  from paddle_serving_server.proto import general_model_config_pb2
  import google.protobuf.text_format
  import os
  import numpy
  import base64
  from PIL import Image
  import io
  from preprocess_ops import Compose
  from postprocess_ops import HRNetPostProcess
  from argparse import ArgumentParser, RawDescriptionHelpFormatter
  import yaml
label_desc: Use image node_id 1 for calling the DetectorOp obj's underlying member method code with example usage: obj.init_op() without return types