SET WINDOW -1.3,1.9,-1.4,1.8
PUBLIC NUMERIC b
DRAW a(17)
END
EXTERNAL PICTURE a(n)
IF n=0 THEN
   SET LINE COLOR b
   PLOT LINES:0,0;1,0
ELSE
   IF n=13 THEN LET b=b+1
   DRAW a(n-1) WITH ROTATE(3*PI/4)*SCALE(1/SQR(2))
   DRAW a(n-1) WITH ROTATE(7*PI/4)*SCALE(1/SQR(2))*SHIFT(1/2,1/2)
END IF
END PICTURE