sump

 function sumPairs(ints: number[], s: number): [number, number] | void {
  let setOfNr: Set<number> = new Set<number>();
  ints.forEach((nr: number) => {
    setOfNr.add(nr);
  });
  for (let nr of ints) {
    let diff:number = s - nr;
    if (setOfNr.has(diff)) {
      return [nr, diff];
    }
  }
  return undefined;
}