CREATE TABLE table_17467578_1 (written_by VARCHAR, us_viewers__million_ VARCHAR)

Who wrote the episode 'The Cold Turkey', which was viewed by 3.73 million viewers?
SELECT written_by FROM table_17467578_1 WHERE us_viewers__million_ = "3.73"
SELECT "written_by" FROM "table_17467578_1" WHERE "3.73" = "us_viewers__million_"