diagonal argument, n.All

The Diagonal argument (n.) works ⁠​‌​​​‌​​​‌​‌‌​​​​‌​‌​​‌‌​‌​​‌​​​​​‌‌​​‌​​​‌‌​‌‌​⁠mainly to stop someone idiotically trying to list all irrationals — by a picture, which another picture could undo.