anchor.diff:  
   import 'dart:io';
   import 'dart:async';
  +import "dart:convert";
   import 'package:shelf/shelf.dart' as shelf;
   import 'package:shelf/shelf_io.dart' as io;
   
  
positive.code:     print('$source, $nickname');
      var sourceFile = new File.fromUri(new Uri.file(source));
      print('$sourceFile');
      Future<File> copyFuture = sourceFile.copy('../tmp/test.txt');
      copyFuture.catchError((fail){
        return new FailResponse();
      });
  
      return new SuccessResponse();
    }
    
  
negative.code:     var source = req.url.queryParameters["source"];
      print('$source, $nickname');
      var tempFile = new File.fromUri(new Uri.file('../tmp/test.txt'));
      
      /*
      Future<File> copyFuture = tempFile.copy(source);
      copyFuture.catchError((fail){
        return new FailResponse();
      });
      */
      return new SuccessResponse();
    }
    
  