如何在不接触外部函数的情况下使代码顺序化

function step1() {
  return new Promise(function(resolve, reject) {
    // 异步操作
    setTimeout(function() {
      console.log('Step 1');
      resolve();
    }, 1000);
  });
}

function step2() {
  return new Promise(function(resolve, reject) {
    // 异步操作
    setTimeout(function() {
      console.log('Step 2');
      resolve();
    }, 1000);
  });
}

function step3() {
  return new Promise(function(resolve, reject) {
    // 异步操作
    setTimeout(function() {
      console.log('Step 3');
      resolve();
    }, 1000);
  });
}

step1()
  .then(step2)
  .then(step3);

function step1() {
  return new Promise(function(resolve, reject) {
    // 异步操作
    setTimeout(function() {
      console.log('Step 1');
      resolve();
    }, 1000);
  });
}

function step2() {
  return new Promise(function(resolve, reject) {
    // 异步操作
    setTimeout(function() {
      console.log('Step 2');
      resolve();
    }, 1000);
  });
}

function step3() {
  return new Promise(function(resolve, reject) {
    // 异步操作
    setTimeout(function() {
      console.log('Step 3');
      resolve();
    }, 1000);
  });
}

async function run() {
  await step1();
  await step2();
  await step3();
}

run();