如何编写一个内部有两个嵌套函数的函数，并让它计算任意数量的给定项目的和/差？

function calculate(...items) {
  // 内部函数将在这里定义
}

function calculate(...items) {
  function sum() {
    // 计算和的逻辑
  }

  function difference() {
    // 计算差的逻辑
  }
}

function calculate(...items) {
  function sum() {
    return items.reduce((total, current) => total + current, 0);
  }

  function difference() {
    // 计算差的逻辑
  }
}

function calculate(...items) {
  function sum() {
    return items.reduce((total, current) => total + current, 0);
  }

  function difference() {
    return items.reduce((total, current) => total - current);
  }
}

function calculate(...items) {
  function sum() {
    return items.reduce((total, current) => total + current, 0);
  }

  function difference() {
    return items.reduce((total, current) => total - current);
  }

  return {
    sum,
    difference
  };
}