Proof using.
induction l; intros; simpl in *; intuition.
- discriminate.
- repeat break_match; subst; eauto.
find_inversion. break_and. subst. eauto.
Qed.

(* Specifications: *)
Lemma get_output_import_O :
forall tr k out,
get_output tr k = Some out ->
In (O k) (import tr).