code: def main(argv=None):
      
      if argv is None:
          argv = sys.argv[1:]
  
      if not argv or argv[0] == "help":
          show_help()
          return 0
      elif argv[0] == "check":
          return check_main(argv[1:])
      elif argv[0] == "list":
          return list_main(argv[1:])
      elif argv[0] == "write":
          return write_main(argv[1:])
      else:
          print(u"Don't understand {!r}".format(" ".join(argv)))
          show_help()
          return 1
docs: The edx_lint command entry point.