code: def main(args):
      env_info = get_sys_env()
      place = (
          "gpu"
          if env_info["Paddle compiled with cuda"]
          and env_info["GPUs used"]
          else "cpu"
      )
  
      paddle.set_device(place)
      if not args.cfg:
          raise RuntimeError("No configuration file specified.")
  
      cfg = Config(args.cfg)
  
      if cfg.dic["data"]["target"]["dataset"] == "cityscapes":
          val_dataset = CityDataset(
              split="val", **cfg.dic["data"]["target"]["kwargs"]
          )
      else:
          raise NotImplementedError()
  
      if len(val_dataset) < 500:
          print(len(val_dataset))
          for i in range(len(val_dataset)):
              print(val_dataset[i])
  
      if val_dataset is None:
          raise RuntimeError(
              "The verification dataset is not specified in the configuration file."
          )
      elif len(val_dataset) == 0:
          raise ValueError(
              "The length of val_dataset is 0. Please check if your dataset is valid"
          )
  
      msg = "\n---------------Config Information---------------\n"
      msg += str(cfg)
      msg += "------------------------------------------------"
      logger.info(msg)
  
      model = cfg.model
      if args.model_path:
          utils.load_entire_model(model, args.model_path)
          logger.info("Loaded trained params of model successfully")
  
      test_config = get_test_config(cfg, args)
  
      val.evaluate(
          model,
          val_dataset,
          num_workers=args.num_workers,
          **test_config,
      )
  
file_path: PaddleSeg/contrib/DomainAdaptation/val.py
imports: import os
  import argparse
  import paddle
  import utils
  from cvlibs import Config
  from script import evaluate
  from paddleseg.cvlibs import manager
  from paddleseg.core import evaluate
  from paddleseg.utils import get_sys_env, logger, utils
  from datasets import CityDataset
  from script import val
label_desc: Use image node_id 3 for calling a global function with example usage: main(args) without return types