code: func (it *And) TagResults(dst map[string]graph.Value) {
  	it.tags.TagResult(dst, it.Result())
  
  	if it.primaryIt != nil {
  		it.primaryIt.TagResults(dst)
  	}
  	for _, sub := range it.internalIterators {
  		sub.TagResults(dst)
  	}
  }
docs: // An extended TagResults, as it needs to add it's own results and
  // recurse down it's subiterators.