code: def main():
      parser = argparse.ArgumentParser(
          description="Compute images mean array"
      )
      parser.add_argument(
          "dataset", help="Path to training image-label list file"
      )
      parser.add_argument(
          "--root",
          "-R",
          default=".",
          help="Root directory path of image files",
      )
      parser.add_argument(
          "--output",
          "-o",
          default="mean.npy",
          help="path to output mean array",
      )
      args = parser.parse_args()
  
      dataset = chainer.datasets.LabeledImageDataset(
          args.dataset, args.root
      )
      mean = compute_mean(dataset)
      np.save(args.output, mean)
  
imports: import argparse
  import sys
  import numpy
  import chainer
label_desc: Use image node_id 2 for calling a global function with example usage: main() without return types