code: def _add_auth_role_arg(arg_parser, default_permissions):
      
      help_text = "Specifies which project permissions to give to the user. Example: 'project_admin'. "
      help_text += "See command list_auth_roles for AuthRole values."
      arg_parser.add_argument("--auth-role",
                              metavar='AuthRole',
                              type=to_unicode,
                              dest='auth_role',
                              help=help_text,
                              default=default_permissions)
docs: Adds optional auth_role parameter to a parser.
      :param arg_parser: ArgumentParser parser to add this argument to.
      :param default_permissions: default value to use for this argument