Exercise 4.4: Recall the definitions of the
special forms and and or from Chapter 1:


 and: The expressions are evaluated from left to right.  If any
expression evaluates to false, false is returned; any remaining expressions are
not evaluated.  If all the expressions evaluate to true values, the value of
the last expression is returned.  If there are no expressions then true is
returned.

 or: The expressions are evaluated from left to right.  If any expression
evaluates to a true value, that value is returned; any remaining expressions
are not evaluated.  If all expressions evaluate to false, or if there are no
expressions, then false is returned.



Install and and or as new special forms for the evaluator by
defining appropriate syntax procedures and evaluation procedures
eval-and and eval-or.  Alternatively, show how to implement
and and or as derived expressions.