Run It With a Pencil

You have used the equals sign for six years to mean that two things are the same, and this year you are using it that way in algebra. A program means something else by it: put this in the box. The proof is one line long — x = x + 1 is nonsense as math and is the commonest line in programming. So: a box with a name on it, what it holds between one line and the next, a loop that changes it ten times, and the oldest bug there is, which loses a value while you watch. Real Python, no computer, and a pencil.