anchor.diff:      }
       var expectationsForUri = _unsatisfiedExpectations[uri];
       if (expectationsForUri == null) return;
  +    offset = _normalizeOffset(offset, _tokenOffsets[uri]);
       var expectationsAtOffset = expectationsForUri[offset];
       if (expectationsAtOffset != null) {
         for (int i = 0; i < expectationsAtOffset.length; i++) {
  
positive.code:     return '/*@$property=${_escape(value.toString())}*/';
    }
  
    void _problem(Uri uri, int offset, String desc, _Fix fix) {
      _problems.add(_formatProblem(uri, offset, desc, null));
      _fixes.putIfAbsent(uri, () => []).add(fix);
  
negative.code:   /// file offset.
    final _testedFeaturesState = <Uri, Map<int, Set<String>>>{};
  
    /// Map from file URI to a sorted list of token offsets for that file.
    final _tokenOffsets = <Uri, List<int>>{};
  
    /// String descriptions of the expectation mismatches found so far.
    final _problems = <String>[];
  
  