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_18646432_4 (written_by VARCHAR, original_air_date VARCHAR)
### Question:
Who wrote the episode originally aired on September 29, 1999?
### Answer:
SELECT written_by FROM table_18646432_4 WHERE original_air_date = "September 29, 1999"