Create a function that takes a string str and modifies the given string as per the below examples:
mumbling("MubAshIr") ➞ "M-Uu-Bbb-Aaaa-Sssss-Hhhhhh-Iiiiiii-Rrrrrrrr"
mumbling("maTT") ➞ "M-Aa-Ttt-Tttt"
mumbling("Sample") ➞ "S-Aa-Mmm-Pppp-Llllll-Eeeeee"
N/A