Let's go back to David in Florida and now he wants an in-ground swimming pool installed. David contacted Pools-R-Us, a company specializing in the sale and construction of in-ground pools. The two parties entered into a contract for labor, services and materials with the work to commence on May 1 and the pool to be fully functional by June 1. On May 5, David lost his job, but was confident he would find another and let Pools-R-Us continue to do the work. After the completion of the work Pools-R-Us wanted to be paid. David could not pay. From Chapter 19, what type of lien can Pools-R-Us use to recover their losses. How would that work?