apply method
Implementation
@override
Future<String> apply(String content, Map<String, dynamic> context) async {
final old = context['old'] as Map<String, dynamic>? ?? {};
return content.replaceAllMapped(RegExp(r"@old\('([\w-]+)'\)"), (match) {
final key = match.group(1) ?? '';
final value = old[key] ?? '';
return value.toString();
});
}