Exercise 4.33: Ben Bitdiddle tests the lazy list
implementation given above by evaluating the expression


(car '(a b c))

To his surprise, this produces an error.  After some thought, he realizes that
the “lists” obtained by reading in quoted expressions are different from the
lists manipulated by the new definitions of cons, car, and
cdr.  Modify the evaluator’s treatment of quoted expressions so that
quoted lists typed at the driver loop will produce true lazy lists.