export function pick<T, K extends keyof T>(obj: T, ...keys: K[]): Pick<T, K> {
  const ret: any = {};
  keys.forEach(key => {
    ret[key] = obj[key];
  });
  return ret;
}

export function isReverseSorted(arr: number[]): boolean {
  const len = arr.length - 1;
  for (let i = 0; i < len; ++i) {
    if (arr[i] < arr[i + 1]) {
      return false;
    }
  }
  return true;
}