Who recognizes this hose?

Dear Scooter friends, Recently my belt was torn and I replaced it with a new one today. This was my first repair, but finally my scooter is running again. (So I would say first half-successful repair ) However, when I took off the Vario cover, I had to push the hoses to the side or remove them from the holders. Unfortunately, I don’t know if and where it has to be connected – even without this cleverness. for a 2 minute test ride. Do you know what this tube is and where it has to go? The tube is open on one side, closed on the other with a cap .. Thank you and best regards Lukas