code: def positional(self, argument_dest, arg_type=None, **kwargs):
          
          self._check_stale()
          if not self._applicable():
              return
  
          if self.command_scope not in self.command_loader.command_table:
              raise ValueError("command authoring error: positional argument '{}' cannot be registered to a group-level "
                               "scope '{}'. It must be registered to a specific command.".format(
                                   argument_dest, self.command_scope))
  
          # Before adding the new positional arg, ensure that there are no existing positional arguments
          # registered for this command.
          command_args = self.command_loader.argument_registry.arguments[self.command_scope]
          positional_args = {k: v for k, v in command_args.items() if v.settings.get('options_list') == []}
          if positional_args and argument_dest not in positional_args:
              raise CLIError("command authoring error: commands may have, at most, one positional argument. '{}' already "
                             "has positional argument: {}.".format(self.command_scope, ' '.join(positional_args.keys())))
  
          deprecate_action = self._handle_deprecations(argument_dest, **kwargs)
          if deprecate_action:
              kwargs['action'] = deprecate_action
  
          kwargs['options_list'] = []
          self.command_loader.argument_registry.register_cli_argument(self.command_scope,
                                                                      argument_dest,
                                                                      arg_type,
                                                                      **kwargs)
docs: Register a positional argument for the given command scope using a knack.arguments.CLIArgumentType
  
          :param argument_dest: The destination argument to add this argument type to
          :type argument_dest: str
          :param arg_type: Predefined CLIArgumentType definition to register, as modified by any provided kwargs.
          :type arg_type: knack.arguments.CLIArgumentType
          :param kwargs: Possible values: `validator`, `completer`, `nargs`, `action`, `const`, `default`,
                         `type`, `choices`, `required`, `help`, `metavar`. See /docs/arguments.md.