final kanjiPattern = RegExp(r'[\u3400-\u4DB5\u4E00-\u9FCB\uF900-\uFA6A]');

List<String> kanjiSuggestions(String string) {
  return kanjiPattern
      .allMatches(string)
      .map((match) => match.group(0))
      .where((element) => element != null)
      .map((element) => element!)
      .toList();
}