anchor.diff:    final StringBuffer errors = StringBuffer();
   
     ValidateCommentCodeSamplesVisitor(
  +    this.analysisHelper,
       this.coreLibName,
       this.filePath,
       this.lineInfo,
  
positive.code: 
  import 'dart:io';
  
  import 'package:analyzer/dart/analysis/features.dart';
  import 'package:analyzer/dart/analysis/results.dart';
  import 'package:analyzer/dart/analysis/utilities.dart';
  
negative.code:       return 'error';
    }
  }
  
  class AnalysisHelper {
    final String libraryName;
    final resourceProvider =
        OverlayResourceProvider(PhysicalResourceProvider.INSTANCE);
    late AnalysisContextCollection collection;
    int index = 0;
  
    AnalysisHelper(this.libraryName) {
      collection = AnalysisContextCollection(
        includedPaths: ['/$libraryName'],
        resourceProvider: resourceProvider,
      );
    }
  
    Future<SomeResolvedUnitResult> resolveFile(String contents) async {
      final samplePath = '/$libraryName/sample_${index++}.dart';
      resourceProvider.setOverlay(
        samplePath,
        content: contents,
        modificationStamp: 0,
      );
  
      var analysisContext = collection.contextFor(samplePath);
      var analysisSession = analysisContext.currentSession;
      return await analysisSession.getResolvedUnit(samplePath);
    }
  }
  