-11. Inspired by our definition of boolean values, propose a data structure
-capable of representing one of the two values "black" or "white". If we have
-one of those values, call it a black-or-white-value, we should be able to
+ (((neg false) 10) 20)
+
+evaluates to 10.
+
+<LI>Define an `and` operator.
+
+<LI>Define an `xor` operator. If you haven't seen this term before, here's a truth table:
+
+ true xor true = false
+ true xor false = true
+ false xor true = true
+ false xor false = false
+
+
+<LI>Inspired by our definition of boolean values, propose a data structure
+capable of representing one of the two values `black` or `white`.
+If we have
+one of those values, call it a "black-or-white value", we should be able to