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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 create(cls, name, protocol_number, protocol_agent=None, comment=None):
 """ Create the IP Service :param str name: name of ip-service :param int protocol_number: ip proto number for this service :param str,ProtocolAgent protocol_agent: optional protocol agent for this service :param str comment: optional comment :raises CreateElementFailed: failure creating element with reason :return: instance with meta :rtype: IPService """

        json = {'name': name,
                'protocol_number': protocol_number,
                'protocol_agent_ref': element_resolver(protocol_agent) or None,
                'comment': comment}

        return ElementCreator(cls, json)