proposition: Lemma remove_1 m x y : K.eq x y -> ~ In y (remove x m).
proof: Proof. intros <-. apply not_in_find. apply remove_spec1. Qed.
imports: Coq(Bool Equalities Orders OrdersFacts OrdersLists) Coq(Morphisms Permutation SetoidPermutation) MMaps(Utils Comparisons Interface)