Raw unicode literals are not supported in Python3

setup.py

@@ -24,6 +24,7 @@ setup(
     url='https://github.com/invisibleroads/socketIO-client',
     install_requires=[
         'requests',
+        'six',
         'websocket-client',
     ],
     packages=find_packages(),

socketIO_client/transports.py

@@ -2,6 +2,7 @@ import json
 import logging
 import re
 import requests
+import six
 import socket
 import time
 import websocket
@@ -11,7 +12,7 @@ from .exceptions import SocketIOError, SocketIOConnectionError, _TimeoutError
 
 
 TRANSPORTS = 'websocket', 'xhr-polling', 'jsonp-polling'
-BOUNDARY = u'\ufffd'
+BOUNDARY = six.u('\ufffd')
 TIMEOUT_IN_SECONDS = 2
 _log = logging.getLogger(__name__)