int rotate(int inchar, int positions_to_rotate) {
    /* or put these declarations outside all functions to make them "global" */
    char* lc_alphabet = "abcdefghijklmnopqrstuvwxyz";
    char* uc_alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    /* look for input character in list of lowercase chars */
    char* in_lc_alphabet = strchr(lc_alphabet, inchar);
    if (in_lc_alphabet != NULL) {
        /* lower-case character:  find rotated char in lc_alphabet */
        int position_in_alphabet = in_lc_alphabet - lc_alphabet;
        /* 
         * YOUR CODE GOES HERE:
         * use lc_alphabet and positions_to_rotate to find new character
         *   and return it
         * strlen(lc_alphabet) may be helpful
         */
    }
    /*
     * YOUR CODE GOES HERE:
     * do something similar to the above for uppercase characters
     * if input character not found in either "alphabet" just return it
     */
}