anchor.diff:  
   import "dart:io";
   import "dart:utf";
  -import "dart:json";
  +import "dart:json" as JSON;
   
   // TODO(hausner): need to select a different port number for each
   // test that runs in parallel.
  
positive.code:       if (errorsDetected) {
          error("Error while handling script entry ${script.currentIndex}");
          error("Message received from debug target: $msg");
          close();
          return;
        }
        if (shutdownEventSeen) {
  
negative.code:     process.stdout.onData = process.stdout.read;
      process.stderr.onData = process.stderr.read;
      process.onExit = (int exitCode) {
        Expect.equals(0, exitCode);
        print("Debug target process exited with exit code $exitCode");
      };
      var debugger = new Debugger(process, debugPort);
      stdin.onClosed = () => debugger.close(killDebugee: true);
      stdin.onError = (error) => debugger.close(killDebugee: true);
      debugger.runScript(script);
    });
    return true;
  