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_23958944_5 (directed_by VARCHAR, no_by_season VARCHAR)
### Question:
Who directed episode 21?
### Answer:
SELECT directed_by FROM table_23958944_5 WHERE no_by_season = 21