Part II: Weighted GPA Calculator (20 points) Write a function gpa.calculator that takes two arguments, in this order 1. grades: A list of strings that represent the letter grades. For simplicity, you only need to think about the letter grades A, B, C, D and F. There will be no grades like B+ or C-, and the grades can be either uppercase or lowercase 2. credits.worth: A list of integers which represent the corresponding credits of the courses with the letter grades given in the grades list. Let's look at an example about how the arguments work together. Suppose grades ['A', 'B', ' and credits-worth = [4, 3, 1 ]This means for the first course the student took and got an , A, in, that course counts for 4 credits; for the second course, for which the student got a B', the class counts for 3 credits; lastly, for the third class, for which the student got a 'f', that class counts for 1 credit CSE 101- Fall 2017 Lab #3 Page 2 Your function should calculate and return the weighted grade point average after converting each grade to a "grade point" in the range 0.0 through 4.0. If the list of grades contains a grade not listed in the table below, or the list of grades is empty, simply return None. Note that the general formula when calculating the GPA is shown below: total number of grade points earned total number of credits attempted You can also check out http://academicanswers.waldenu.edu/faq/73219 for an example on how to calculate the GPA