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diff --git a/src/Util/ListUtil/FoldBool.v b/src/Util/ListUtil/FoldBool.v
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+Require Import Coq.Lists.List.
+
+Lemma fold_left_orb_true ls
+  : List.fold_left orb ls true = true.
+Proof. induction ls as [|?? IHls]; [ reflexivity | assumption ]. Qed.
+Lemma fold_left_orb_pull ls v
+  : List.fold_left orb ls v = orb v (List.fold_left orb ls false).
+Proof. destruct v; [ apply fold_left_orb_true | reflexivity ]. Qed.