proposition: Lemma equivlistA_nil_eq l : equivlistA eqA l [] → l ≡ [].
proof: Proof. induction l. easy. intros E. edestruct equivlistA_cons_nil; eauto. Qed.
imports: Coq.Lists.List Coq.Lists.SetoidList MathClasses.interfaces.abstract_algebra MathClasses.interfaces.monads MathClasses.theory.monads