ジェネリクス

型引数（type parameters）を受け取る関数を作る機能

const repeatStr = (value: string, times: number): string[] => {
  return new Array(times).fill(value);
}

const repeatNum = (value: number, times: number): number[] => {
  return new Array(times).fill(value);
}

const repeatT = <T>(value: T, times: number): T[] => {
  return new Array(times).fill(value);
}

  console.log(repeatT<number>(10,3));