code: func (it *Optional) NextPath(ctx context.Context) bool {
  	if it.lastCheck {
  		ok := it.subIt.NextPath(ctx)
  		if !ok {
  			it.err = it.subIt.Err()
  		}
  		return ok
  	}
  	return false
  }
docs: // An optional iterator only has a next result if, (a) last time we checked
  // we had any results whatsoever, and (b) there was another subresult in our
  // optional subbranch.