FIX: Get rid of basestring (not python3 compatible).

dav_events/converters.py

@@ -1,6 +1,7 @@
 import datetime
 import logging
 import re
+from six import string_types
 
 logger = logging.getLogger(__name__)
 
@@ -53,7 +54,7 @@ class Iso8601Serializer(object):
     @classmethod
     def deserialize(cls, value, ignore_unsupported_input=False):
         prefix = '{marker}{sep}'.format(marker=cls.marker, sep=cls.separator)
-        if isinstance(value, basestring) and value.startswith(prefix):
+        if isinstance(value, string_types) and value.startswith(prefix):
             haystack = value[len(prefix):]
             m = cls._re.match(haystack)
             if m is not None:
@@ -68,6 +69,6 @@ class Iso8601Serializer(object):
             elif not ignore_unsupported_input:
                 raise ValueError('Format not recognized \'{str}\''.format(str=haystack))
         elif not ignore_unsupported_input:
-            raise ValueError('Expected basestring,'
+            raise ValueError('Expected string type,'
                              ' not {}'.format(value.__class__.__name__))
         return value