What is the episode number of the episode that originally aired on February 4, 2008?
CREATE TABLE "season_2" (
  "production_no" real,
  "episode_no" real,
  "original_airdate" text,
  "episode_title" text,
  "host" text
);
SELECT "episode_no" FROM "season_2" WHERE "original_airdate"='february 4, 2008';