private void AddClassification(LocatedNode node, IClassificationType classificationType)
        {
            if (classificationType == null)
                throw new ArgumentNullException(nameof(classificationType));

            if (node.SourceRange.Length > 0 && node.Span.IsInRootFile)
                _results.Add(CreateClassificationTagSpan(node, classificationType));
        }
 private ITagSpan<IClassificationTag> CreateClassificationTagSpan(LocatedNode node, IClassificationType classificationType)
 {
     var snapshotSpan = new SnapshotSpan(_snapshot, node.Span.Start, node.Span.Length);
     var classificationTag = new ClassificationTag(classificationType);
     return new TagSpan<ClassificationTag>(snapshotSpan, classificationTag);
 }