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_name_56 (date VARCHAR, machine VARCHAR, rider VARCHAR)
### Question:
Harry l Stephen rides a Norton machine on what date?
### Answer:
SELECT date FROM table_name_56 WHERE machine = "norton" AND rider = "harry l stephen"