code: func (p StreamPath) SplitLast() (StreamPath, string) {
  	if idx := strings.LastIndex(string(p), StreamNameSepStr); idx > 0 {
  		return p[:idx], string(p[idx+len(StreamNameSepStr):])
  	}
  	return "", string(p)
  }
docs: // SplitLast splits the rightmost component from a StreamPath, returning the
  // intermediate StreamPath.
  //
  // If the path begins with a leading separator, it will be included in the
  // leftmost token. Note that such a path is invalid.
  //
  // If there are no components in the path, ("", p) will be returned.