Exercise $1\mathrm{.}20.$ Write a function that swaps the values of three int variables.

It should have the following prototype:

void $,$ int $**b,$ int $**c)$;

For example, calling swap$3($&x$,$ &y$,$ &z$)$ should result in z$\text{'}$s having y$\text{'}$s orig$-$

inal value, y$\text{'}$s having x$\text{'}$s original value, and x$\text{'}$s having z$\text{'}$s original value. Use

assertions to protect the function. Write a unit test of swap$3$ in a main func$-$

tion. Illustrate various interesting memory configurations during its execution.

How can swap$3$ be called in order to swap the values of two variables rather

than three, given that three arguments must be passed? This problem consists of three parts: $($a$)$ a C program as specified in the problem. Your code should be in a file named swap$3.$c $($b$)$ stack configurations: show two stack configurations, one before your first call to swap$3$ function, and one just before returning from the first call $($c$)$ answer the question on the last line of the problem regarding the use of your function for swapping two values.