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type SubscribedEvent = (...args) => any;

class EventObserver {
    public events: SubscribedEvent[] = [];

    subscribe(fn: SubscribedEvent) {
      this.events.push(fn)
    }

    unsubscribe(fn: SubscribedEvent) {

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/**
 * Класс Singleton предоставляет метод getInstance, который позволяет клиентам
 * получить доступ к уникальному экземпляру одиночки.
 */
class Singleton {
    private static instance: Singleton;

    /**
     * Конструктор Singleton должен быть приватный, чтобы кто-нибудь случайно не создал
     * объект через оператор new.

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interface IParticle {
    element: HTMLElement;
    size: number;
    horizontalSpeed: number;
    speedUp: number;
    spinVal: number;
    spinSpeed: number;
    top: number;
    left: number;
    direction: -1 | 1;

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/**
 * Our subscription type. This is to manage teardowns.
 */
class Subscription {
  private teardowns = new Set<() => void>();
 
  add(teardown: () => void) {
    this.teardowns.add(teardown);
  }
 

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const source = (subscriber: Observer<string>) => {
  const socket = new WebSocket('wss://echo.websocket.org');
 
  socket.onopen = () => {
    socket.send('Hello, World!');
  };
 
  socket.onmessage = (e) => {
    subscriber.next(e.data);
  };

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const helloSocket = new Observable<string>((subscriber) => {
  // Open a socket.
  const socket = new WebSocket('wss://echo.websocket.org');
 
  socket.onopen = () => {
    // Once it's open, send some text.
    socket.send('Hello, World!');
  };
 
  socket.onmessage = (e) => {

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class SafeSubscriber<T> {
  closed = false;
 
  constructor(private destination: Partial<Observer<T>>) {}
 
  next(value: T) {
    if (!this.closed) {
      this.destination.next?.(value);
    }
  }

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interface Observer<T> {
  next: (value: T) => void;
  complete: () => void;
  error: (err: any) => void;
}

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class SafeSubscriber<T> {
  closed = false;
 
  constructor(private destination: Partial<Observer<T>>) {}
 
  next(value: T) {
    if (!this.closed) {
      this.destination.next?.(value); // Note the ?. check here.
    }
  }

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/**
 * A class used to wrap a user-provided Observer. Since the
 * observer is just a plain objects with a couple of callbacks on it,
 * this type will wrap that to ensure `next` does nothing if called after
 * `complete` has been called, and that nothing happens if `complete`
 * is called more than once.
 */
class SafeSubscriber<T> {
  closed = false;