old_contents: #!/usr/bin/env python
  import os
  
  TOOLS_DIR = os.path.dirname(os.path.abspath(__file__))
  CHAL_DIR = os.path.join(os.path.dirname(TOOLS_DIR), 'cqe-challenges')
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
new_contents: #!/usr/bin/env python
  import argparse
  import os
  import sys
  
  TOOLS_DIR = os.path.dirname(os.path.abspath(__file__))
  CHAL_DIR = os.path.join(os.path.dirname(TOOLS_DIR), 'cqe-challenges')
  TEST_DIR = os.path.join(TOOLS_DIR, 'cb-testing')
  
  
  def test_challenges(chals):
      # type: (list) -> None
      pass
  
  
  def listdir(path):
      # type: (str) -> list
      if not os.path.isdir(path):
          return []
      return sorted(os.listdir(path))
  
  
  def main():
      parser = argparse.ArgumentParser()
  
      g = parser.add_mutually_exclusive_group(required=True)
      g.add_argument('-a', '--all', action='store_true',
                     help='Run tests against all challenge binaries')
  
      g.add_argument('-c', '--chals', nargs='+', type=str,
                     help='List of challenge names to test')
  
      args = parser.parse_args(sys.argv[1:])
  
      if args.all:
          test_challenges(listdir(CHAL_DIR))
      elif args.chals:
          test_challenges(args.chals)
  
  
  if __name__ == '__main__':
      main()
  
subject: Add tester args