Who is the music by for episode the Elbow Room?
CREATE TABLE "america_rock" (
  "episode_title" text,
  "subject" text,
  "music_by" text,
  "lyrics_by" text,
  "performed_by" text,
  "first_aired" text
);
SELECT "music_by" FROM "america_rock" WHERE "episode_title"='Elbow Room';