Please implement and test the expression tree class from Project 1 on
page 529 of Chapter 10 of the textbook. The
expression tree must include a constructor that makes an expression
tree from a prefix expression. (Alternative if you document it: you
can have a constructor that makes an expression tree from a postfix expression).
Sample Assignment: Expression Trees
Data Structures and Other Objects Using C++
by Michael Main and Walter Savitch
You may work with another student to create one header file and one
test program that you both will use, but the implementation of the
expression tree functions must be done entirely on your own.