code: func NormalizeIdentifier(s string) string {
  	if s == "" {
  		return s
  	}
  
  	str := regValidIdentifier.ReplaceAllString(s, underscore)
  
  	// it needs to be started with letter
  	// if not, prepend `The_`
  	startedWithLetter := func() bool {
  		r := []rune(str)
  		return unicode.IsLetter(r[0])
  	}()
  	if !startedWithLetter && !strings.HasPrefix(str, "[]") {
  		str = "The_" + str
  	}
  
  	return strings.Trim(str, "_")
  }
docs: // NormalizeIdentifier change invalid character in identifier
  // to `_`.
  // Edge cases:
  // - If started with invalid char, we prepend with `The_`
  // - don't replace `.` if it means a library