anchor.diff:  
     Future<CompilerOutput> _compileExpression(
         _CompileExpressionRequest request) async {
  -    _stdoutHandler.reset();
  +    _stdoutHandler.reset(suppressCompilerMessages: true);
   
       // 'compile-expression' should be invoked after compiler has been started,
       // program was compiled.
  
positive.code:   final CompilerMessageConsumer consumer;
    String boundaryKey;
    Completer<CompilerOutput> compilerOutput;
  
    void handler(String string) {
      const String kResultPrefix = 'result ';
  
negative.code:           string.substring(boundaryKey.length + 1, spaceDelimiter),
            int.parse(string.substring(spaceDelimiter + 1).trim())));
      }
      else if (!_suppressCompilerMessages) {
        consumer('compiler message: $string');
      }
    }
  
    // This is needed to get ready to process next compilation result output,
    // with its own boundary key and new completer.
    void reset({bool suppressCompilerMessages = false}) {
      boundaryKey = null;
      compilerOutput = new Completer<CompilerOutput>();
      _suppressCompilerMessages = suppressCompilerMessages;
    }
  }
  
  