code: def match(self, passageId):
          
          if not isinstance(passageId, CtsReference):
              passageId = CtsReference(passageId)
  
          if self.is_root():
              return self[passageId.depth-1]
          return self.root.match(passageId)
docs: Given a passageId matches a citation level
  
          :param passageId: A passage to match
          :return: