CREATE TABLE table_1490 ("No. in series" TEXT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original airdate" TEXT, "Production code" TEXT)

Who was the writer of the episode number in series 4?
SELECT "Written by" FROM table_1490 WHERE "No. in series" = '4'
SELECT "Written by" FROM "table_1490" WHERE "No. in series" = '4'