class Cell {
  var value: int;
  
  predicate p { acc(value) }
  
  method test()
    requires p
  {
    var tmp: int := unfolding p in value;
    var tmp2: int := unfolding p in value;
    call void()
    assert tmp == unfolding p in value // ERROR: should fail
  }
  
  method test2()
    requires p
  {
    var tmp: int := unfolding p in value;
    var tmp2: int := unfolding p in value;
    call v()
    assert tmp == unfolding p in value
  }
  
  method v() requires true {}
  
  method void()
    requires p
    ensures p
  {}
  
}