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

Lemma ZOOOPST_singleton_inl :
forall A B C h i,
@zero_or_one_outputs_per_step_trace A B C [(h, inl i)].