Samuel orally agrees to sell his house to Betty for $250,000, with the deal to close 30 days later (that is, Samuel will deliver the deed to the house and Betty will pay $250,000 at that time). When the day of closing arrives, Samuel refuses to deliver the deed to Betty. Betty sues for breach of contract. Without a written contact of sale, the contract is unenforceable. What could Betty argue as an exception to the writing requirement, thus allowing the court to enforce the oral contract between Betty and Samuel?