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export async function mapFastAsyncFn(fn, arr){  const promised = arr.map((a, i) => fn(a, i))
  return Promise.all(promised)}
export function mapFastAsync(fn, arr){  if (arguments.length === 1){    return async holder => mapFastAsyncFn(fn, holder)  }
  return new Promise((resolve, reject) => {    mapFastAsyncFn(fn, arr).then(resolve)      .catch(reject)  })}