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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_directory_list_doc(self, configs):
 """JSON dict description of a protorpc.remote.Service in list format. Args: configs: Either a single dict or a list of dicts containing the service configurations to list. Returns: dict, The directory list document as a JSON dict. """


    if not isinstance(configs, (tuple, list)):
      configs = [configs]

    util.check_list_type(configs, dict, 'configs', allow_none=False)

    return self.__directory_list_descriptor(configs)