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_20 (constructor VARCHAR, chassis VARCHAR, driver VARCHAR)
### Question:
Who constructed the car that Derek Warwick raced in with a TG181 chassis?
### Answer:
SELECT constructor FROM table_name_20 WHERE chassis = "tg181" AND driver = "derek warwick"