**
Quiz 11, 11/8
**

The program FibonacciStack.java
simulates the pushing and popping of activation records that takes place during the execution of
the standard, recursive function to compute the `n`th Fibonacci number.
While this program simulates the system stack, it does not actually compute the `n`th Fibonacci number,
it just returns 0.
Modify the program so that in addition to what it is currently doing, it also does the following:

- Whenever it prints out "pop," it should also print out the Fibonacci number corresponding to the
activation record being popped. For example, for
`n` = 4, we should see output such as:
push 4
push 3
push 2
pop: answer = 1
push 1
pop: answer = 1
pop: answer = 2
push 2
pop: answer = 1
pop: answer = 3

In this output, the line `pop: answer = 2` states the fact that the activation record corresponding
to `n` = 3 is being popped and the 3rd Fibonacci number is 2.

- The function should actually return the
`n`th Fibonacci number, rather than 0.