code: def collate_inputs(self, inputs):
      collate_inputs = {k: [] for k in inputs[0].keys()}
      for info in inputs:
          for k in collate_inputs.keys():
              collate_inputs[k].append(info[k])
      return {
          k: np.stack(v)
          for k, v in collate_inputs.items()
          if k in GLOBAL_VAR["feed_vars"]
      }
  
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 4 for calling the DetectorOp obj's underlying member method code with example usage: obj.collate_inputs(inputs) and returns: unknown