use six to support python 2 and 3

ox/web/duckduckgo.py

@@ -1,17 +1,17 @@
 # -*- coding: utf-8 -*-
 # vi:si:et:sw=4:sts=4:ts=4
 import re
-import urllib
+
+from six.moves import urllib
 import ox
 from ox import strip_tags, decode_html
-from ox.utils import json
 from ox.cache import read_url
 
 
 def find(query, timeout=ox.cache.cache_timeout):
-    if isinstance(query, unicode):
+    if not isinstance(query, bytes):
         query = query.encode('utf-8')
-    params = urllib.urlencode({'q': query})
+    params = urllib.parse.urlencode({'q': query})
     url = 'http://duckduckgo.com/html/?' + params
     data = read_url(url, timeout=timeout).decode('utf-8')
     results = []