1uniqid() -> "4n5pxq24kpiob12og9"
2uniqid('hello-') -> "hello-4n5pxq24kpiob12og9"
3uniqid('hello-', '-goodbye') -> "hello-4n5pxq24kpiob12og9-goodbye"
4
5// usage with suffix only
6uniqid('', '-goodbye') -> "4n5pxq24kpiob12og9-goodbye"
7uniqid(undefined, '-goodbye') -> "4n5pxq24kpiob12og9-goodbye"