anchor.diff:        NodeChangeForAsExpression();
   
     @override
  +  NodeChange visitCompilationUnit(CompilationUnit node) =>
  +      NodeChangeForCompilationUnit();
  +
  +  @override
     NodeChange visitDefaultFormalParameter(DefaultFormalParameter node) =>
         NodeChangeForDefaultFormalParameter();
   
  
positive.code:   }
  }
  
  /// Implementation of [NodeChange] specialized for operating on
  /// [CompilationUnit] nodes.
  class NodeChangeForCompilationUnit extends NodeChange<CompilationUnit> {
    NodeChangeForCompilationUnit() : super._();
  
    bool removeLanguageVersionComment = false;
  
    @override
    EditPlan _apply(CompilationUnit node, FixAggregator aggregator) {
  
negative.code:     }
      innerPlans.addAll(aggregator.innerPlansForNode(node));
      return aggregator.planner.passThrough(node, innerPlans: innerPlans);
    }
  }
  
  