code: func (c *ChromeTarget) Subscribe(method string, callback func(*ChromeTarget, []byte)) {
  	c.eventLock.Lock()
  	c.eventDispatcher[method] = callback
  	c.eventLock.Unlock()
  }
docs: // Subscribe Events, you must know the method name, such as Page.loadFiredEvent, and bind a function
  // which takes a ChromeTarget (us) and the raw JSON byte data for that event.