How to use the textfsm.terminal.Usage function in textfsm

# Page text supplied in either specified file or stdin.

  if len(args) == 1:
    with open(args[0], 'r') as f:
      fd = f.read()
  else:
    fd = sys.stdin.read()
  Pager(fd, delay=isdelay).Page()


if __name__ == '__main__':
  help_msg = '%s [--help] [--size] [--nodelay] [input_file]\n' % sys.argv[0]
  try:
    sys.exit(main())
  except Usage as err:
    print(err, file=sys.stderr)
    print('For help use --help', file=sys.stderr)
    sys.exit(2)

if opt in ('-h', '--help'):
      print(__doc__)
      print(help_msg)
      return 0

  isdelay = False
  for opt, _ in opts:
    # Prints the size of the terminal and returns.
    # Mutually exclusive to the paging of text and overrides that behaviour.
    if opt in ('-s', '--size'):
      print('Length: %d, Width: %d' % TerminalSize())
      return 0
    elif opt in ('-d', '--delay'):
      isdelay = True
    else:
      raise Usage('Invalid arguments.')

  # Page text supplied in either specified file or stdin.

  if len(args) == 1:
    with open(args[0], 'r') as f:
      fd = f.read()
  else:
    fd = sys.stdin.read()
  Pager(fd, delay=isdelay).Page()

def main(argv=None):
  """Routine to page text or determine window size via command line."""

  if argv is None:
    argv = sys.argv

  try:
    opts, args = getopt.getopt(argv[1:], 'dhs', ['nodelay', 'help', 'size'])
  except getopt.error as msg:
    raise Usage(msg)

  # Print usage and return, regardless of presence of other args.
  for opt, _ in opts:
    if opt in ('-h', '--help'):
      print(__doc__)
      print(help_msg)
      return 0

  isdelay = False
  for opt, _ in opts:
    # Prints the size of the terminal and returns.
    # Mutually exclusive to the paging of text and overrides that behaviour.
    if opt in ('-s', '--size'):
      print('Length: %d, Width: %d' % TerminalSize())
      return 0
    elif opt in ('-d', '--delay'):