code: function WrappedWorker(script, onMessage, onError) {
  		var wUrl = new URL(script, window.location.href);
  		wUrl = new URL(urlModifier(wUrl.href));
  		wUrl.query.set("worker-language",  ((navigator.languages && navigator.languages[0]) ||
  			navigator.language || navigator.userLanguage || 'root').toLowerCase()); //$NON-NLS-1$
  		this.worker = new Worker(wUrl.href);
  		this.worker.onmessage = onMessage.bind(this);
  		this.worker.onerror = onError.bind(this);
  		this.worker.postMessage({
  			request: "start_worker"
  		});
  		this.messageId = 0;
  		this.callbacks = Object.create(null);
  	}
docs: for add and removes only 
  @description Make a new worker