CREATE TABLE table_27237 ("No." FLOAT, "#" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( million ) " TEXT)

What is the production code of the episode that had 5.43 million viewers?
SELECT "Production code" FROM table_27237 WHERE "U.S. viewers (million)" = '5.43'
SELECT "Production code" FROM "table_27237" WHERE "U.S. viewers (million)" = '5.43'