+ * @param string $key Key built via makeKey() or makeGlobalKey()
+ * @param int $exptime Time-to-live (in seconds) or a UNIX timestamp expiration
+ * @param int $value Amount to increase the key value by [default: 1]
+ * @param int|null $init Value to initialize the key to if it does not exist [default: $value]
+ * @param int $flags Bit field of class WRITE_* constants [optional]