who are the writers of the episode that had 3.07 millions of North American spectators?
CREATE TABLE table_21979779_1 (written_by VARCHAR, us_viewers__million_ VARCHAR)
SELECT written_by FROM table_21979779_1 WHERE us_viewers__million_ = "3.07"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_21979779_1 (written_by VARCHAR, us_viewers__million_ VARCHAR) Question: who are the writers of the episode that had 3.07 millions of North American spectators? [/INST] SELECT written_by FROM table_21979779_1 WHERE us_viewers__million_ = "3.07" </s>