uniqid() -> "4n5pxq24kpiob12og9"
uniqid('hello-') -> "hello-4n5pxq24kpiob12og9"
uniqid('hello-', '-goodbye') -> "hello-4n5pxq24kpiob12og9-goodbye"

// usage with suffix only
uniqid('', '-goodbye') -> "4n5pxq24kpiob12og9-goodbye"
uniqid(undefined, '-goodbye') -> "4n5pxq24kpiob12og9-goodbye"