internal/scanner/scanner.go
func TokenString(tok rune) string {
	if s, ok := tokenString[tok]; ok {
		return s
	}
	return fmt.Sprintf("%q", string(tok))
}
func TokenString(tok rune) string {
	if s, ok := tokenString[tok]; ok {
		return s
	}
	return fmt.Sprintf("%q", string(tok))
}
// TokenString returns a printable string for a token or Unicode character.