What is the production code of the title "secret weapons"?
CREATE TABLE "table1_19229713_6" (
  "no" real,
  "num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" text,
  "u_s_viewers_million" text
);
SELECT "production_code" FROM "table1_19229713_6" WHERE "title"='\"Secret Weapons\"';