code: function moveBindingIndexToReservedSlot(offset) {
      var currentSlot = viewData[BINDING_INDEX];
      viewData[BINDING_INDEX] = tView.bindingStartIndex - offset;
      return currentSlot;
  }
docs: Sets up the binding index before executing any `pureFunctionX` instructions.
  
  The index must be restored after the pure function is executed
  
  {@link reserveSlots}