$4\mathrm{.}17$ LAB: Departments

A company assigns a letter to each of its organizational departments as shown in the figure. Write a Python program that uses a text prompt to ask the user for one of the $8$ letters used. Check that the user has entered one of those allowed letters, but it can be upper$-$case or lower$-$case; if not, print a sentence indicating that an "error" occurred and then end without printing anything else. For allowed letters, use a cascaded if structure to convert that letter into a string, according to the table below. Store the string in a string variable. Then, after the if structure, print out a sentence that indicates the name of the department