Describe the process that Smalltalk goes through in
looking up a method when a message is sent to an object A.
(Be sure to allow for the fact that the method may have been inherited
by a superclass.)
Solution
Each object has a reference to the object representing its class.
Suppose A's reference is to B.
The interpreter will go to B from A and ask B
whether its method dictionary contains the requested method.
If not, then from B it gets the class object representing
B's superclass, and it asks it whether it contains the
requested method. It continues this up the hierarchy, stopping when the
requested method is found (or if it exhausts the hierarchy with no
success).