(*Require Import VST.floyd.unfold_data_at.*)
Local Open Scope logic.
Fixpoint fold_right_sepcon' (l: list(environ->mpred)) : environ -> mpred :=
match l with
| nil => emp
| b::nil => b
| b::r => b * fold_right_sepcon' r
end.

Lemma orp_dup {A}{ND: NatDed A}: forall P: A, P || P = P.