code: func GoroutineID() uint64 {
  	b := make([]byte, 64)
  	b = b[:runtime.Stack(b, false)]
  	// Parse the 4707 out of "goroutine 4707 ["
  	b = bytes.TrimPrefix(b, goroutineSpace)
  	i := bytes.IndexByte(b, ' ')
  	if i < 0 {
  		panic(fmt.Sprintf("No space found in %q", b))
  	}
  	b = b[:i]
  	n, err := strconv.ParseUint(string(b), 10, 64)
  	if err != nil {
  		panic(fmt.Sprintf("Failed to parse goroutine ID out of %q: %v", b, err))
  	}
  	return n
  }
docs: // GoroutineID returns current GO Routine ID (parsed from runtime.Stack)