Proof using.
unfold zero_or_one_outputs_per_step_trace, zero_or_one_outputs_per_step.
simpl in *.
intuition. subst. simpl in *. find_inversion. auto.
Qed.

(* Specifications: *)
Lemma ZOOOPST_singleton_singleton :
forall A B C h x,
@zero_or_one_outputs_per_step_trace A B C [(h, inr [x])].