Create a function called roman_digit that takes a letter (I, V, X, L, C, D, or M, or the lowercase version of any of these) and returns its decimal value. If the character is not one of those listed, the function should return 0. Function name: roman_digit Input argument: a single character representing a Roman digit. May be either upper or lower case Output argument: a scalar integer value, the decimal value of the Roman digit Reminder of the weights of Roman digits: 1 = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000