CREATE TABLE table_3632 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Director" TEXT, "Writer ( s ) " TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( million ) " TEXT)

What was the u.s. viewers (millions) when the production code was 4alh19?
SELECT "U.S. viewers (million)" FROM table_3632 WHERE "Production code" = '4ALH19'
SELECT "U.S. viewers (million)" FROM "table_3632" WHERE "Production code" = '4ALH19'