Add _compat module for 2.x / 3.x compatibility

Author: tony

qencode/_compat.py

@@ -0,0 +1,10 @@
+# flake8: NOQA
+import sys
+
+PY2 = sys.version_info[0] == 2
+
+
+if PY2:
+    string_types = (str, unicode)
+else:
+    string_types = (str,)