Fats Waller makes a pretty good case for being one of the inventors of jazz. He certainly wrote most of the early jazz hits, including this one.
Rumor has it that Fats was so popular he was hired by Al Capone to play for a party in the apartment of the mob boss, where he was not allowed to leave for three days. In the end, Fats was reportedly very well paid for the gig, but he wasn't sure he was going to get out of there alive.
Anyway, this is an icon of the Great American Songbook. Enjoy.