Account numbers sometimes contain a check digit that is the result of a mathematical calculation. The inclusion of the digit in an account number helps ascertain whether the number is a valid one. Write an application named CheckDigit that asks a user to enter a four-digit account number and determines whether it is a valid number. The number is valid if the fourth digit is the remainder when the number represented by the first three digits of the four-digit number is divided by 7. For example, 7770 is valid, because 0 is the remainder when 777 is divided by 7. If the account number is valid, output The account number is valid. If the account number is invalid output Invalid. If the account number is too short or too long output Account number invalid - it must have 4 digits.

Develop the program incrementally: a) start by reading and displaying each line of the input file to make sure you are reading the data set correctly. b) use the split string method to extract information from each line into a list. print the list to prove that this step is working correctly. d) convert the exam scores to type int and calculate the student’s average. display those items to prove this step is working correctly. e) create a tuple containing the six items for each student (name, exam scores, exam mean). display the tuples to prove this step is working correctly. (optionally, you may want to have the exam scores in a list so your tuple is (name, scores_list, f) append each tuple to a list. display the list to prove this step is working correctly. g) use the sort list method to re-order the tuples in the list. display the list to prove this step is working correctly. h) use a for statement to display the contents of the list as a table (with appropriate formatting). i) use a for statement to calculate the average of all scores on exam #1, then display the results. note that you could have calculated this average within the first loop, but we are explicitly requiring you to do this calculation by looping though your list of tuples. j) add the logic to calculate the average of all scores on exam #2, then display the results.