diff --git a/cas_server/default_settings.py b/cas_server/default_settings.py
index 750a9c9..a773573 100644
--- a/cas_server/default_settings.py
+++ b/cas_server/default_settings.py
@@ -105,7 +105,7 @@ try:
 except AttributeError:
     __CAS_FEDERATE_PROVIDERS_LIST = list(settings.CAS_FEDERATE_PROVIDERS.keys())
 
-    def __CAS_FEDERATE_PROVIDERS_LIST_sort(key):
+    def __cas_federate_providers_list_sort(key):
         if len(settings.CAS_FEDERATE_PROVIDERS[key]) > 2:
             key = settings.CAS_FEDERATE_PROVIDERS[key][2].lower()
         else:
@@ -113,11 +113,11 @@ except AttributeError:
         if isinstance(key, six.string_types) or isinstance(key, six.text_type):
             return tuple(
                 int(num) if num else alpha
-                for num, alpha in __CAS_FEDERATE_PROVIDERS_LIST_sort.tokenize(key)
+                for num, alpha in __cas_federate_providers_list_sort.tokenize(key)
             )
         else:
             return key
-    __CAS_FEDERATE_PROVIDERS_LIST_sort.tokenize = re.compile(r'(\d+)|(\D+)').findall
-    __CAS_FEDERATE_PROVIDERS_LIST.sort(key=__CAS_FEDERATE_PROVIDERS_LIST_sort)
+    __cas_federate_providers_list_sort.tokenize = re.compile(r'(\d+)|(\D+)').findall
+    __CAS_FEDERATE_PROVIDERS_LIST.sort(key=__cas_federate_providers_list_sort)
 
     setting_default('CAS_FEDERATE_PROVIDERS_LIST', __CAS_FEDERATE_PROVIDERS_LIST)
diff --git a/cas_server/federate.py b/cas_server/federate.py
index 3aed3ae..453a778 100644
--- a/cas_server/federate.py
+++ b/cas_server/federate.py
@@ -46,7 +46,7 @@ class CASFederateValidateUser(object):
         """test `password` agains the user"""
         if self.client is None:
             return False
-        username, attributs, pgtiou = self.client.verify_ticket(ticket)
+        username, attributs = self.client.verify_ticket(ticket)[:2]
         if username is not None:
             if attributs is None:
                 attributs = {}
@@ -73,7 +73,8 @@ class CASFederateValidateUser(object):
         else:
             return False
 
-    def register_slo(self, username, session_key, ticket):
+    @staticmethod
+    def register_slo(username, session_key, ticket):
         FederateSLO.objects.create(
             username=username,
             session_key=session_key,
@@ -82,10 +83,10 @@ class CASFederateValidateUser(object):
 
     def clean_sessions(self, logout_request):
         try:
-            SLOs = self.client.get_saml_slos(logout_request)
+            slos = self.client.get_saml_slos(logout_request)
         except NameError:
-            SLOs = []
-        for slo in SLOs:
+            slos = []
+        for slo in slos:
             try:
                 for federate_slo in FederateSLO.objects.filter(ticket=slo.text):
                     session = SessionStore(session_key=federate_slo.session_key)
diff --git a/cas_server/utils.py b/cas_server/utils.py
index aa9f8f4..9487ec8 100644
--- a/cas_server/utils.py
+++ b/cas_server/utils.py
@@ -73,7 +73,9 @@ def reverse_params(url_name, params=None, **kwargs):
         return url
 
 
-def copy_params(get_or_post_params, ignore=set()):
+def copy_params(get_or_post_params, ignore=None):
+    if ignore is None:
+        ignore = set()
     params = {}
     for key in get_or_post_params:
         if key not in ignore and get_or_post_params[key]:
@@ -96,7 +98,9 @@ def set_cookie(response, key, value, max_age):
     )
 
 
-def get_current_url(request, ignore_params=set()):
+def get_current_url(request, ignore_params=None):
+    if ignore_params is None:
+        ignore_params = set()
     protocol = 'https' if request.is_secure() else "http"
     service_url = "%s://%s%s" % (protocol, request.get_host(), request.path)
     if request.GET:
@@ -184,11 +188,11 @@ def gen_saml_id():
     return _gen_ticket('_')
 
 
-def get_tuple(tuple, index, default=None):
-    if tuple is None:
+def get_tuple(nuplet, index, default=None):
+    if nuplet is None:
         return default
     try:
-        return tuple[index]
+        return nuplet[index]
     except IndexError:
         return default
 
diff --git a/cas_server/views.py b/cas_server/views.py
index 0d41620..f1434b0 100644
--- a/cas_server/views.py
+++ b/cas_server/views.py
@@ -193,7 +193,8 @@ class FederateAuth(View):
     def dispatch(self, request, *args, **kwargs):
         return super(FederateAuth, self).dispatch(request, *args, **kwargs)
 
-    def get_cas_client(self, request, provider):
+    @staticmethod
+    def get_cas_client(request, provider):
         if provider in settings.CAS_FEDERATE_PROVIDERS:
             service_url = utils.get_current_url(request, {"ticket", "provider"})
             return CASFederateValidateUser(provider, service_url)