;; Print some numbers.
 (loop for i from 1 to 3
       do (print i))
 |>  1
 |>  2
 |>  3
⇒  NIL

;; Print every third number.
 (loop for i from 10 downto 1 by 3
       do (print i))
 |>  10 
 |>  7 
 |>  4 
 |>  1 
⇒  NIL

;; Step incrementally from the default starting value.
 (loop for i below 3
       do (print i))
 |>  0
 |>  1
 |>  2
⇒  NIL