export async function filter<T>(
  arr: T[],
  iterator: (item: T) => Promise<boolean>,
) {
  const fail = Symbol("fail");
  return (
    await Promise.all(
      arr.map(async (item) => ((await iterator(item)) ? item : fail)),
    )
  ).filter((i) => i !== fail) as any as Promise<T[]>;
}

export const delay = (ms: number) => new Promise((res) => setTimeout(res, ms));