anchor.diff:        messageLines++;
       }
       message.write(']');
  +    numMessages++;
  +    final attributes = {
  +      if (line == lines.length) 'num_messages': numMessages.toString()
  +    };
       var base64data = base64Encode(utf8.encode(message.toString()));
  -    var jsonMessage =
  -        '{"messages": [{"attributes": {}, "data": "$base64data"}]}';
  +    var messageObject = {
  +      'messages': [
  +        {'attributes': attributes, 'data': base64data}
  +      ]
  +    };
  +    var jsonMessage = jsonEncode(messageObject);
       var headers = {'Authorization': 'Bearer $token'};
       var response =
           await client.post(postUrl, headers: headers, body: jsonMessage);
  
positive.code:     usage(parser);
    }
  
    var client = http.Client();
  
    var lines = await File(options['result_file']).readAsLines();
    var token = await File(options['auth_token']).readAsString();
    // Construct pubsub messages.
    var line = 0;
    while (line < lines.length) {
      var message = StringBuffer();
      message.write('[');
      message.write(lines[line++]);
      var messageLines = 1;
  
negative.code:     print('Status ${response.statusCode}');
      print('Response: ${response.body}');
    }
    print('Number of Pub/Sub messages sent: $numMessages');
    client.close();
  }
  