Using C++ programming

(17\%) Write a program (file name: Q4.cpp) with a recursive function string cycles (char ch);. The parameter ch is always a lowercase letter a-z. The function would return a string which "cycles" from parameter ch down to letter ' a ' then back to letter ch again. The following shows some sample function calls and the expected return string contents. Note: - You cannot use any for-loop, while-loop, or do-while-loop in this question. - What you write in the main () function is unimportant. It may contain code to test-call the required function. We shall grade only the required function