code: func parseBlockTitle(l string) (title string, ok bool) {
  	t := strings.TrimSuffix(l, ":")
  	if len(t) == len(l) || len(t) == 0 {
  		return // doesn't end in ':' or just ':' itself
  	}
  	// Check it has no space and the first rune is capital.
  	for pos, r := range t {
  		if unicode.IsSpace(r) || (pos == 0 && !unicode.IsUpper(r)) {
  			return
  		}
  	}
  	return t, true
  }
docs: // parseBlockTitle recognizes strings like "Args:" that indicate the beginning
  // of a named block.
  //
  // We are pretty strict here to avoid misfiring on ':' that appear in sentences:
  //   * The title should start with the upper case ("Args", not "args").
  //   * No spaces allowed ("Returns", not "Return value").