code: public long addAndGet(long delta)
        throws MemcachedException, InterruptedException, TimeoutException {
      if (delta >= 0) {
        return this.memcachedClient.incr(this.key, delta, this.initialValue);
      } else {
        return this.memcachedClient.decr(this.key, -delta, this.initialValue);
      }
    }
docs: Add value and get the result
  
  @param delta
  @return
  @throws MemcachedException
  @throws InterruptedException
  @throws TimeoutException