有人能告诉我我的RXJS代码是如何工作的吗？

import { Observable } from 'rxjs';

// 创建一个可观察对象
const observable = new Observable(observer => {
  observer.next(1);
  observer.next(2);
  observer.next(3);
  setTimeout(() => {
    observer.next(4);
    observer.complete();
  }, 1000);
});

// 订阅可观察对象
const subscription = observable.subscribe({
  next: x => console.log('收到值: ' + x),
  error: err => console.error('发生错误: ' + err),
  complete: () => console.log('完成')
});

// 取消订阅
setTimeout(() => {
  subscription.unsubscribe();
}, 1500);

const subscription = observable.subscribe(...);
// 在适当的时候取消订阅
subscription.unsubscribe();

const subscription = observable.subscribe({
  next: x => console.log('收到值: ' + x),
  error: err => console.error('发生错误: ' + err),
  complete: () => console.log('完成')
});

const result = observable.pipe(
  map(x => x * 2),
  filter(x => x > 2)
);