anchor.diff:      ],
       'causal-async-stacks': [
         _boolValues,
  -      _setSaneAsyncStacks,
  +      _setCausalAsyncStacks,
         (debugger, _) => debugger.saneAsyncStacks
       ],
  +    'awaiter-stacks': [
  +      _boolValues,
  +      _setAwaiterStacks,
  +      (debugger, _) => debugger.awaiterStacks
  +    ]
     };
   
     static Future _setBreakOnException(debugger, name, value) async {
  
positive.code:   void updateStackFrames(S.ServiceMap newStack) {
      List frameElements = _frameList.children;
      List newFrames;
      if (_debugger.saneAsyncStacks &&
          (newStack[ObservatoryDebugger.kAsyncCausalStackFrames] != null)) {
        newFrames = newStack[ObservatoryDebugger.kAsyncCausalStackFrames];
      } else {
  
negative.code: 
    void _loadSettings() {
      _upIsDown = settings.get('up-is-down');
      _causalAsyncStacks = settings.get('causal-async-stacks') ?? true;
      _awaiterStacks = settings.get('awaiter-stacks') ?? true;
    }
  
    S.VM get vm => page.app.vm;
  