old_contents: #!/usr/bin/python3
  
  # Copyright 2021 Google Inc.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     https://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  """Entry point for various tools useful for J2CL development."""
  
  import argparse
  
  import bench
  import diff
  import make_size_report
  import replace_all
  import test_all
  import test_integration
  
  
  def _add_cmd(subparsers, name, handler, descr):
    parser = subparsers.add_parser(name, help=descr, description=descr)
    if hasattr(handler, "add_arguments"):
      handler.add_arguments(parser)
    parser.set_defaults(func=handler.main)
  
  
  if __name__ == "__main__":
    base_parser = argparse.ArgumentParser(description="j2 dev script.")
    parsers = base_parser.add_subparsers()
  
    _add_cmd(parsers, "size", make_size_report, "Generate size report.")
    _add_cmd(parsers, "gen", replace_all, "Regenerate readable examples.")
    _add_cmd(parsers, "bench", bench, "Run a benchmark.")
    _add_cmd(parsers, "diff", diff, "Compare output.")
    _add_cmd(parsers, "test", test_integration, "Run an integration test.")
    _add_cmd(parsers, "testall", test_all, "Run all tests.")
  
    # TODO(goktug): Add presubmit cmd to run various tasks needed before submit.
    # TODO(goktug): Add WASM deobfuscation support.
    # TODO(goktug): Add top level filter for different backends (--platform).
  
    args = base_parser.parse_args()
    if not hasattr(args, "func"):
      base_parser.error("too few arguments")
    args.func(args)
  
new_contents: #!/usr/bin/python3
  
  # Copyright 2021 Google Inc.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     https://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  """Entry point for various tools useful for J2CL development."""
  
  import argparse
  import sys
  
  import bench
  import diff
  import make_size_report
  import replace_all
  import test_all
  import test_integration
  
  
  def _add_cmd(subparsers, name, handler, descr):
    parser = subparsers.add_parser(name, help=descr, description=descr)
    if hasattr(handler, "add_arguments"):
      handler.add_arguments(parser)
    parser.set_defaults(func=handler.main)
  
  
  if __name__ == "__main__":
    base_parser = argparse.ArgumentParser(description="j2 dev script.")
    parsers = base_parser.add_subparsers()
  
    _add_cmd(parsers, "size", make_size_report, "Generate size report.")
    _add_cmd(parsers, "gen", replace_all, "Regenerate readable examples.")
    _add_cmd(parsers, "bench", bench, "Run a benchmark.")
    _add_cmd(parsers, "diff", diff, "Compare output.")
    _add_cmd(parsers, "test", test_integration, "Run an integration test.")
    _add_cmd(parsers, "testall", test_all, "Run all tests.")
  
    # TODO(goktug): Add presubmit cmd to run various tasks needed before submit.
    # TODO(goktug): Add WASM deobfuscation support.
    # TODO(goktug): Add top level filter for different backends (--platform).
  
    args = base_parser.parse_args()
    if not hasattr(args, "func"):
      base_parser.print_help(sys.stderr)
      sys.exit(1)
    args.func(args)
  
subject: Make the j2.py script show its help information when no arguments are supplied by the user