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:

a.  Add some segments to the primitive wave painter of exercise  2.49 
    (to add a smile, for example).

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).

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.)

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Skipped.