Who directed the episode written by Dan Serafin and aired on July 23, 2008?
CREATE TABLE "season_1_2007_2009" (
  "prod_no" text,
  "title" text,
  "written_by" text,
  "directed_by" text,
  "original_airdate" text
);
SELECT "directed_by" FROM "season_1_2007_2009" WHERE "written_by"='dan serafin' AND "original_airdate"='july 23, 2008';