anchor.diff:      _wrap('write($variable, $writtenType, $writtenExpression)',
           () => _wrapped.write(variable, writtenType, writtenExpression));
     }
  +
  +  @override
  +  void _dumpState() => _wrapped._dumpState();
   
     T _wrap<T>(String description, T callback(),
         {bool isQuery: false, bool? isPure}) {
  
positive.code: class FlowAnalysisDebug<Node extends Object, Statement extends Node,
          Expression extends Object, Variable extends Object, Type extends Object>
      implements FlowAnalysis<Node, Statement, Expression, Variable, Type> {
    _FlowAnalysisImpl<Node, Statement, Expression, Variable, Type> _wrapped;
  
    bool _exceptionOccurred = false;
  
  
negative.code:   /// necessary; in this case, [viaInitializer] should be `true`.
    void write(
        Variable variable, Type writtenType, Expression? writtenExpression);
  
    /// Prints out a summary of the current state of flow analysis, intended for
    /// debugging use only.
    void _dumpState();
  }
  
  /// Alternate implementation of [FlowAnalysis] that prints out inputs and output
  