basestring not supported in python 3.8

flask_cas/routing.py

@@ -127,6 +127,10 @@ def validate(ticket):
         attributes = xml_from_dict.get("cas:attributes", {})
 
         if attributes and "cas:memberOf" in attributes:
+            try:
+                basestring
+            except NameError:
+                basestring = str
             if isinstance(attributes["cas:memberOf"], basestring):
                 attributes["cas:memberOf"] = attributes["cas:memberOf"].lstrip('[').rstrip(']').split(',')
                 for group_number in range(0, len(attributes['cas:memberOf'])):