At the risk of sound really dumb, I have a question about the corer. I just got mine yesterday and I can see how to use it to core an apple or whatever. But I don't get how to use it with a cucumber. The use/care card just says to put it "over" the cucumber (sliced in half) and remove the seeds. Can someone explain to me how it's supposed to work? Do you just scrape it with the corer from one side down to the other? if so, why not just use a knife? I'm confused..... TIA, Deb