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 unsigned_repr_range: forall i, 0 <= i -> 0 <= Ptrofs.unsigned (Ptrofs.repr i) <= i.