Definition nonlocal (Q: environ->mpred) := True.Ltac check_nonlocal :=
  match goal with
  |  |- nonlocal (local _) => fail 1
  |  |- nonlocal (prop _) => fail 1
  |  |- nonlocal (andp _ _) => fail 1
  |  |- nonlocal (sepcon _ _) => fail 1
  | |- _ => apply I
 end.

Lemma finish_canon: forall R1 P Q R, do_canon `(R1) (PROPx P (LOCALx Q (SEPx R))) = (PROPx P (LOCALx Q (SEPx (R1::R)))).