six: py3compat imports BytesIO and StringIO from six
@@ -19,6 +19,9 @@ from six import integer_types
from six import string_types
from six import text_type
+from six import BytesIO
+from six import StringIO
+
from six.moves.urllib.parse import urldefrag
from six.moves.urllib.parse import urljoin
from six.moves.urllib.parse import urlparse
