code: def nextId(self):
          
          if self._next_id is False:
              # Request the next urn
              self._prev_id, self._next_id = self.getPrevNextUrn(reference=self.urn.reference)
          return self._next_id
docs: Shortcut for getting the following passage identifier
  
          :rtype: CtsReference
          :returns: Following passage reference