func (l *Lexer) skipWhitespace() {
	for unicode.Is(unicode.White_Space, l.next()) {
	}
	l.backup()
	l.ignore()
}
func (l *Lexer) skipWhitespace() {
	for unicode.Is(unicode.White_Space, l.next()) {
	}
	l.backup()
	l.ignore()
}
// skipWhitespace ignores all whitespace characters