Write a command-driven driver to implement the test plan written for Exercise 2. A command-driven program is one in which the user enters the operation to be tested followed by the values to use in the test. For example, to test if the Add method correctly adds 1/2 and 3/4, the user might input

+ 1 2 3 4

The operation is invoked with the appropriate data, and the result is written on the screen. The user is prompted to enter another operation or quit.