docs: private void removeActivityFromStack(Activity activity){
  
  		Iterator<WeakReference<Activity>> activityStackIterator = activityStack.iterator();
  		while(activityStackIterator.hasNext()){
  			Activity activityFromWeakReference = activityStackIterator.next().get();
  
  			if(activityFromWeakReference == null){
  				activityStackIterator.remove();
  			}
  
  			if(activity != null && activityFromWeakReference != null && activityFromWeakReference.equals(activity)){
  				activityStackIterator.remove();
  			}
  		}
  	}