Output: puzzle mixing async functions, nested awaits, then chains, queueMicrotask and setTimeout

1async function a1() {
2  console.log('a1 start');
3  await a2();
4  console.log('a1 end');
5}
6async function a2() {
7  console.log('a2');
8}
9console.log('script start');
10setTimeout(() => console.log('timeout'), 0);
11a1();
12new Promise((resolve) => {
13  console.log('p1');
14  resolve();
15})
16  .then(() => console.log('then1'))
17  .then(() => console.log('then2'));
18queueMicrotask(() => console.log('micro'));
19console.log('script end');