1 (define (below painter1 painter2)
2   (let* ( (split-point (make-vect 0.0 0.5))
3 	  (paint-up 
4 	   (transform-painter
5 	    painter2
6 	    (make-vector 0.0 0.0)
7 	    (make-vector 1.0 0.0)
8 	    split-point))
9 	  (paint-down
10 	   (transform-painter
11 	    painter1
12 	    split-point
13 	    (make-vector 1.0 0.5)
14 	    (make-vector 0.0 1.0))))
15     (lambda (frame)
16       (paint-up frame)
17       (paint-down frame))))
18 (define (below-rot painter1 painter2)
19   (rotate90 (beside
20 	     (rotate270 painter1)
21 	     (rotate270 painter2))))
22 
23  Exercise 2.52.  Make changes to the square limit of wave shown in figure 2.9 by working at each of the levels described above. In particular:
24 
25 a.  Add some segments to the primitive wave painter of exercise  2.49 (to add a smile, for example).
26 
27 b.  Change the pattern constructed by corner-split (for example, by using only one copy of the up-split and right-split images instead of two).
28 
29 c.  Modify the version of square-limit that uses square-of-four so as to assemble the corners in a different pattern. (For example, you might make the big Mr. Rogers look outward from each corner of the square.)