Below procedure
Define the 
below
 operation for painters. 
Below
 takes two painters as arguments. The resulting painter, given a frame, draws with the first painter in the bottom of the frame and with the second painter in the top. Define 
below
 in two different ways -- first by writing a procedure that is analogous to the 
beside
 procedure given above, and again in terms of 
beside
 and suitable rotation operations (from exercise 
2.50
).