CREATE TABLE table_73324 ("No." FLOAT, "#" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "U.S. viewers  ( million ) " TEXT, "Original air date" TEXT, "Production code" FLOAT)

Who wrote the episode with the production code 519?
SELECT "Written by" FROM table_73324 WHERE "Production code" = '519'
SELECT "Written by" FROM "table_73324" WHERE "Production code" = '519'