CREATE TABLE table_name_56 (year INT, role VARCHAR, director VARCHAR)

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