code: def parse(self, args):
          
          if args is None:
              args = self._default_args
          if isinstance(args, six.string_types):
              args = shlex.split(args)
          return args
docs: :param args: arguments
          :type args: None or string or list of string
          :return: formatted arguments if specified else ``self.default_args``
          :rtype: list of string