如何在Dart中将列表中的两个连续元素转换为Map中的条目？

void main() {
  List<String> list = ['key1', 'value1', 'key2', 'value2', 'key3', 'value3'];

  Map<String, String> map = list.fold({}, (result, element) {
    if (element is String) {
      if (result.isEmpty) {
        result[element] = '';
      } else {
        result[result.keys.last] = element;
      }
    }
    return result;
  });

  print(map);
}

{key1: value1, key2: value2, key3: value3}