Non-primitive VS that take a step.

program_logic/viewshifts.v

@@ -12,6 +12,13 @@ Notation "P ={ E }=> Q" := (P ={E,E}=> Q)%I
   (at level 99, E at level 50, Q at level 200,
    format "P  ={ E }=>  Q") : uPred_scope.
 
+Notation "P ={ E1 , E2 }▷=> Q" := (P ={E1%I,E2%I}=> ▷ |={E2,E1}=> Q)%I
+  (at level 99, E1, E2 at level 50, Q at level 200,
+   format "P ={ E1 , E2 }▷=>  Q") : uPred_scope.
+Notation "P ={ E }▷=> Q" := (P ={E,E}▷=> Q)%I
+  (at level 99, E at level 50, Q at level 200,
+   format "P ={ E }▷=>  Q") : uPred_scope.
+
 Section vs.
 Context `{irisG Λ Σ}.
 Implicit Types P Q R : iProp Σ.