proposition: Lemma ZOOOPST_nil : forall A B C, @zero_or_one_outputs_per_step_trace A B C [].
proof: Proof. Proof using. unfold zero_or_one_outputs_per_step_trace, zero_or_one_outputs_per_step. simpl. intuition. Qed.
imports: Verdi(Verdi HandlerMonad)