code: def get_parents_for(self, child_ids):
          
          self._cache_init()
          parent_candidates = []
          for parent, children in self._cache_get_entry(self.CACHE_NAME_PARENTS).items():
              if set(children).intersection(child_ids):
                  parent_candidates.append(parent)
          return set(parent_candidates)
docs: Returns parent aliases for a list of child IDs.
  
          :param list child_ids:
          :rtype: set
          :return: a set of parent aliases