info_tren/lib/utils/string_number_prefix.dart

extension NumberPrefix on String {
  String get numberPrefix {
    final sb = StringBuffer();
    for (final c in this.runes) {
      if ('0'.runes.first <= c && c <= '9'.runes.first) {
        sb.writeCharCode(c);
      }
      else {
        break;
      }
    }
    return sb.toString();
  }
}