In Varni Bros. Corp. v. Wine World, Inc. (1995) 35 Cal.App.4th 880, the court further explained the limitations on these rules: "Where a written contract states a term clearly and unambiguously, usage or custom that would vary or contradict the term is not admissible. Similarly, where the parties contradict each other on whether a certain term was part of a contract based on their precontract discussions, usage or custom is not admissible to prove that one party's version of the terms of the contract was more probable. " (Varni, supra, 35 Cal.App.4th at p. 889-890.) In that case, the court of appeal found neither situation present because there was neither a written contract expressly covering the subject at hand (termination of implied distributing agreements) nor was there any discussion by the parties regarding the subject. (Id. at p. 890.)