code: func init() {
  	// We'll use zero width joiners.
  	runewidth.ZeroWidthJoiner = true
  
  	// Initialize the predefined input field handlers.
  	InputFieldInteger = func(text string, ch rune) bool {
  		if text == "-" {
  			return true
  		}
  		_, err := strconv.Atoi(text)
  		return err == nil
  	}
  	InputFieldFloat = func(text string, ch rune) bool {
  		if text == "-" || text == "." || text == "-." {
  			return true
  		}
  		_, err := strconv.ParseFloat(text, 64)
  		return err == nil
  	}
  	InputFieldMaxLength = func(maxLength int) func(text string, ch rune) bool {
  		return func(text string, ch rune) bool {
  			return len([]rune(text)) <= maxLength
  		}
  	}
  }
docs: // Package initialization.