(define hilbert '((to hilbert (size level parity) (if (> level 0) ((left (* parity 90)) (hilbert size (- level 1) (- parity)) (forward size) (right (* parity 90)) (hilbert size (- level 1) parity) (forward size) (hilbert size (- level 1) parity) (right (* parity 90)) (forward size) (hilbert size (- level 1) (- parity)) (left (* parity 90)) ) ) ) (hilbert 10 4 1) ))