fact: Fixpoint map_contains env (x y : N) (m : map_expr) : option term := match m with | Empty => None | Add x' y' f' m' => if (N.eqb x (term_denote env x') && N.eqb y (term_denote env y'))%bool then Some f' else map_contains env x y m' end.
imports: Coq.NArith.NArith Coq.FSets.FMaps Coq.micromega.Lia Category.Lib Category.Lib.FMapExt