I think I remember now how those hash thingies work, kinda like a dictionary... but how can that remove the duplicates?? sorry I didn't get that part, I'm still new to perl...
Hashes remove duplicates because hashes have keys - you can't have 2 keys that are the same. If you try to add another key=value pair to the hash where the key already exists, the new key=value will just overwrite the old one.