proposition: Lemma NoDupA_eqk_eqke : forall l, NoDupA eqk l -> NoDupA eqke l.
proof: Proof. induction 1; auto. constructor; auto. destruct x as (k,e). eauto using InA_eqke_eqk. Qed.
imports: Bool DecidableType DecidableTypeEx OrderedType Morphisms FMapInterface