def format_help(self):
    """Override help doc to add cell args. """

    if not self._cell_args:
      return super(CommandParser, self).format_help()
    else:
      # Print the standard argparse info, the cell arg block, and then the epilog
      # If we don't remove epilog before calling the super, then epilog will
      # be printed before the 'Cell args' block.
      epilog = self.epilog
      self.epilog = None
      orig_help = super(CommandParser, self).format_help()

      cell_args_help = '\nCell args:\n\n'
      for cell_arg, v in six.iteritems(self._cell_args):
        required = 'Required' if v['required'] else 'Optional'
        cell_args_help += '%s: %s. %s.\n\n' % (cell_arg, required, v['help'])

      orig_help += cell_args_help
      if epilog:
        orig_help += epilog + '\n\n'
      return orig_help
Override help doc to add cell args.