This command adds 1 to the number that is associated with the given
key. The numeric value must a 64-bit signed integer.
keydoes not exist, the associated string is set to “0”.
keyis associated with a non-string value, or if its associated string cannot be converted to an integer, an error is raised.
Returns the value after addition.
$ SET yugakey 7
$ INCRBY yugakey 3