code: def main():
      parser = argparse.ArgumentParser()
      parser.add_argument("input")
      parser.add_argument("sample_output", help="train output file")
      parser.add_argument("remainder_output", help="valid output file")
      parser.add_argument("-k", type=int, help="remainder size")
      parser.add_argument(
          "--lines",
          action="store_true",
          help="split lines instead of docs",
      )
      args = parser.parse_args()
  
      assert args.k is not None
  
      sample = []
      remainder = []
      num_docs = [0]
  
      def update_sample(doc):
          if len(sample) < args.k:
              sample.append(doc.copy())
          else:
              i = num_docs[0]
              j = random.randrange(i + 1)
              if j < args.k:
                  remainder.append(sample[j])
                  sample[j] = doc.copy()
              else:
                  remainder.append(doc.copy())
          num_docs[0] += 1
          doc.clear()
  
      with open(args.input, "r", encoding="utf-8") as h:
          doc = []
          for i, line in enumerate(h):
              if (
                  line.strip() == ""
              ):  # empty line indicates new document
                  update_sample(doc)
              else:
                  doc.append(line)
              if args.lines:
                  update_sample(doc)
              if i % 1000000 == 0:
                  print(i, file=sys.stderr, end="", flush=True)
              elif i % 100000 == 0:
                  print(".", file=sys.stderr, end="", flush=True)
          if len(doc) > 0:
              update_sample(doc)
      print(file=sys.stderr, flush=True)
  
      assert len(sample) == args.k
  
      with open(args.sample_output, "w", encoding="utf-8") as out:
          first = True
          for doc in sample:
              if not first and not args.lines:
                  out.write("\n")
              first = False
              for line in doc:
                  out.write(line)
  
      with open(args.remainder_output, "w", encoding="utf-8") as out:
          first = True
          for doc in remainder:
              if not first and not args.lines:
                  out.write("\n")
              first = False
              for line in doc:
                  out.write(line)
  
label_desc: Use image node_id 1 for calling a global function with example usage: main() without return types