'Beverly Hillbillies' and more sitcoms that featured folk music

The release of the Coen brothers' new film, "Inside Llewyn Davis," has sparked renewed interest in the folk-music scene of the early 1960s (a concert honoring the movie and its era airs Friday on Showtime). Back in the day, though, the times were indeed a-changin' as some of TV's best-known sitcoms were "hip" enough to even incorporate folk music into their plots: