docs: public void init(long maxValue, int machineNum) {
  		this.size = maxValue;
  		switch (machineNum) {
  		case BitMap.MACHINE32:
  			bm = new IntMap((int) (size / machineNum));
  			break;
  		case BitMap.MACHINE64:
  			bm = new LongMap((int) (size / machineNum));
  			break;
  		default:
  			throw new RuntimeException("Error Machine number!");
  		}
  	}