Write a function $($average$\_$grades$)$ that takes a dictionary where the keys are student names and the values are lists of their exam scores, calculates the average score for each student, saves that information in a new dictionary, and returns the new dictionary.

Outside of the function, create a sample dictionary of student names and grades, call the average$\_$grades function on that dictionary, and iterate over the returned dictionary to print each student's name and average score with two decimal places.