code: public static DispatchQueue createBackgroundQueue(String name, DispatchQueueType type) {
  		if (type == DispatchQueueType.Serial) {
  			return new SerialDispatchQueue(name);
  		}
  		if (type == DispatchQueueType.Concurrent) {
  			return new ConcurrentDispatchQueue(name);
  		}
  
  		throw new IllegalArgumentException("Unexpected queue type: " + type);
  	}
docs: Creates a background queue with specified <code>name</code> and dispatch type.