Facio Ut Des
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
(Lat. I do that you may give.) A species of contract in the civil law (being one of the innominate contracts) which occurs when a man agrees to perform anything for a price either specifically mentioned or left to the determination of the law to set a value on it; as when a servant hires himself to his master for certain wages or an agreed sum of money.
2 BL Comm. 445.