Retrieve the siblings of a textual node

        :param textId: CtsTextMetadata Identifier
        :param reference: CapitainsCtsPassage Reference
        :return: GetPrevNextUrn request response from the endpoint

def getSiblings(self, textId, subreference):
        """ Retrieve the siblings of a textual node

        :param textId: CtsTextMetadata Identifier
        :param reference: CapitainsCtsPassage Reference
        :return: GetPrevNextUrn request response from the endpoint
        """
        textId = "{}:{}".format(textId, subreference)
        return self.getPrevNextUrn(urn=textId)