Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
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?
### Answer:
SELECT written_by FROM table_21979779_1 WHERE us_viewers__million_ = "3.07"