Danny Holgate plays a section of George Gershwin’s “Ain’t Necesarily So” from Porgy and Bess, a song sung by a Cab inspired character, in an outtake from the documentary Cab Calloway: Sketches. Cab Calloway: Sketches premieres nationally Monday, February 27 at 10 p.m. (ET) on PBS (check local listings). In the New York metro-area the film airs Sunday, February 26 at 8 p.m. on THIRTEEN.