A dock with a do-over button

Last night I'm tying off a trawler in some port I don't recognize, and every line I throw slips, every knot comes undone mid-loop. The harbor master keeps handing me a little brass lever labeled 'do-over'. No resistance, no price, just a fresh try, clean hands. I must have pulled it forty times before I woke up. Just a dream, but I keep thinking: what would we not give to resplice a bad morning line?