self.frz_since.map_or(false, |loc_t| loc_t <= acc_t),
Mut(acc_m) =>
// Raw pointers are fine with frozen locations. This is important because &Cell is raw!
self.frz_since.map_or(false, |loc_t| loc_t <= acc_t),
Mut(acc_m) =>
// Raw pointers are fine with frozen locations. This is important because &Cell is raw!