Ask HN: Method/Tool to test if a link has already been submitted to HN

I'm a long time observer to HN and just starting to comment and submit. I'm wondering if a method or tool exists to test if a url has already been submitted to HN. I've tried using the url as a search parameter for HN but with no luck. I'm imagining the ability to paste the url (that I intend to submit) into a box, click a button and be told if it is a duplicate. Thanks.