code: def getSiblings(self, textId, subreference: CtsReference):
          
          text, inventory = self.__getText__(textId)
          if not isinstance(subreference, CtsReference):
              subreference = CtsReference(subreference)
          passage = text.getTextualNode(subreference)
          return passage.siblingsId
docs: Retrieve the siblings of a textual node
  
          :param textId: CtsTextMetadata Identifier
          :type textId: str
          :param subreference: CapitainsCtsPassage CtsReference
          :type subreference: str
          :return: Tuple of references
          :rtype: (str, str)