Increment the key with floating point precision.
自增一个浮点型的数值。
Parameters
key
value: (float) value that will be added to the key
Return value
FLOAT the new value
Examples
$redis->incrByFloat('key1', 1.5); /* key1 didn't exist, so it will now be 1.5 */
$redis->incrByFloat('key1', 1.5); /* 3 */
$redis->incrByFloat('key1', -1.5); /* 1.5 */
$redis->incrByFloat('key1', 2.5); /* 3.5 */
