py3 fix: use six StringIO import

Author: manu-chroma

schema_salad/makedoc.py

@@ -7,7 +7,7 @@
 import copy
 import re
 import sys
-from StringIO import StringIO
+
 import logging
 
 from . import schema
@@ -16,6 +16,7 @@
 import six
 from six.moves import range
 from six.moves.urllib import parse
+from six import StringIO
 
 from typing import cast, Any, Dict, IO, List, Optional, Set, Text, Union
 

schema_salad/ref_resolver.py

@@ -9,12 +9,13 @@
 import six
 from six.moves import range
 import urllib
-# import urlparse
+
 from six.moves.urllib import parse
+from six import StringIO
 
 import re
 import copy
-from StringIO import StringIO
+
 
 from . import validate
 from schema_salad.utils import aslist, flatten

schema_salad/tests/test_cli_args.py

@@ -4,9 +4,9 @@
 
 import schema_salad.main as cli_parser
 
-""" for capturing print() output """
+# for capturing print() output
 from contextlib import contextmanager
-from StringIO import StringIO
+from six import StringIO
 
 @contextmanager
 def captured_output():