What is the title of the episode/s written by Michael Gans & Richard Register?
CREATE TABLE table_23399481_4 (
    title VARCHAR,
    written_by VARCHAR
)
SELECT title FROM table_23399481_4 WHERE written_by = "Michael Gans & Richard Register"
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What is the title of the episode/s written by Michael Gans & Richard Register? ### Input: CREATE TABLE table_23399481_4 (
    title VARCHAR,
    written_by VARCHAR
) ### Response: SELECT title FROM table_23399481_4 WHERE written_by = "Michael Gans & Richard Register"