def fix_filenames(t):
        import os
        os.chdir(t)
        for f in sorted(os.listdir()):
                file_name, file_ext = (os.path.splitext(f))
                if file_ext == ".mp3":
                        test = file_name.split("-")
                        if len(test) == 3:
                                try:
                                        int(test[0])
                                        del(test[0])
                                        f_title, f_course = test
                                        print("{}-{}{}".format(f_course, f_title, file_ext))
                                        new_name = "{}-{}{}".format(f_course, f_title, file_ext)
                                        os.rename(f, new_name)
                                except:
                                        pass