code: public synchronized int removeSubscriber(String eventName, IGenericEvent<T> subscriber) {
          List<IGenericEvent<T>> subscribers = getSubscribers(eventName, false);
          
          if (subscribers != null) {
              subscribers.remove(subscriber);
              
              if (subscribers.isEmpty()) {
                  subscriptions.remove(eventName);
              }
              
              return subscribers.size();
          }
          
          return -1;
      }
docs: Removes a subscriber from the specified event.
  
  @param eventName Name of the event.
  @param subscriber Subscriber to remove.
  @return Count of subscribers after the operation, or -1 no subscriber list existed.