What is the production code for the episode whose original air date was May15,2000?
CREATE TABLE "table1_29391888_1" (
  "series_num" real,
  "season_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" text
);
SELECT "production_code" FROM "table1_29391888_1" WHERE "original_air_date"='May15,2000';