anchor.diff:    @override
     void visitFunctionExpression(FunctionExpression node) {
       // There are no completions.
  +    data.recordPercentage(
  +        'Functions with type parameters', node.typeParameters != null);
       super.visitFunctionExpression(node);
     }
   
  
positive.code: 
    @override
    void visitExtensionDeclaration(ExtensionDeclaration node) {
      _recordDataForNode('ExtensionDeclaration (type)', node.extendedType);
      for (var member in node.members) {
        _recordDataForNode('ExtensionDeclaration (member)', member,
  
negative.code:   /// with the same lexeme to the number of times that distance was found.
    Map<int, int> tokenDistances = {};
  
    /// A table mapping percentage data names to the percentage data collected.
    Map<String, _PercentageData> percentageData = {};
  
    /// Initialize a newly created set of relevance data to be empty.
    RelevanceData();
  
    /// Increment the count associated with the given [name] by one.
    void incrementCount(String name) {
  