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 (year INTEGER, role VARCHAR, director VARCHAR)
### Question:
What year was the role nan taylor, alias of nan ellis, aka mrs. andrews and directed by William keighley?
### Answer:
SELECT SUM(year) FROM table_name_56 WHERE role = "nan taylor, alias of nan ellis, aka mrs. andrews" AND director = "william keighley"