What movie was the music of Llewyn Davis thought to have descended from ?
" The humorous novelty song " Please Mr. Kennedy " , a plea from a reluctant astronaut , appears to be a fourth generation derivative of the 1960 song " Mr. Custer " , also known as " Please Mr. Custer " , about the Battle of the Little Bighorn , sung by Larry Verne and written by Al DeLory , Fred Darian , and Joseph Van Winkle .