Testing (rot13, series, lambda, ack)

This test file will not run with the rot13.py included in your ['rot13' branch](https://github.com/yonayen/sea-c28-students/blob/974db74c3561bb62c6844eba4fba75163a063e83/Students/YonathanAyenew/rot13.py) because that module does not contain a function called `rot13`.