Changes since the book version: 1. The variable "_" contains the result of the last top-level expression evaluation, so you can re-use intermediate values without re-typing them. 2. for statement added, just like the one in C. 3. ++ and -- added. 4. Interrupts are caught; use cntrl-D to quit. 5. % operator added. 6. +=, -=, etc., added. 7. \ at end of line eats newline