Write a recursive function progress_bar(completion_percent) that takes an int completion_percent. The function should return a string progress bar representing the completion percentage. The beginning and end of the completion bar should be square brackets [ and ]. Each ten percent of completion will be represented by one character in the progress bar. Thus, every progress bar should be ten characters long. Use hashmarks # to represent the completion percentage and use blank spaces to represent the remaining work to be completed. You should always 'round down' the completion number to the nearest ten (see hint below). You do not need to deal with inputs below 0 or above 100