diff --git a/filter_plugins/custom.py b/filter_plugins/custom.py
index 22177cdd..443627b0 100644
--- a/filter_plugins/custom.py
+++ b/filter_plugins/custom.py
@@ -1,11 +1,12 @@
-__author__ = 'dale mcdiarmid'
+__author__ = "dale mcdiarmid"
 
 import re
 import os.path
 from six import string_types
 
-def modify_list(values=[], pattern='', replacement='', ignorecase=False):
-    ''' Perform a `re.sub` on every item in the list'''
+
+def modify_list(values=[], pattern="", replacement="", ignorecase=False):
+    """ Perform a `re.sub` on every item in the list"""
     if ignorecase:
         flags = re.I
     else:
@@ -13,45 +14,62 @@ def modify_list(values=[], pattern='', replacement='', ignorecase=False):
     _re = re.compile(pattern, flags=flags)
     return [_re.sub(replacement, value) for value in values]
 
-def append_to_list(values=[], suffix=''):
+
+def append_to_list(values=[], suffix=""):
     if isinstance(values, string_types):
-        values = values.split(',')
-    return [str(value+suffix) for value in values]
+        values = values.split(",")
+    return [str(value + suffix) for value in values]
 
-def array_to_str(values=[],separator=','):
+
+def array_to_str(values=[], separator=","):
     return separator.join(values)
 
-def extract_role_users(users={},exclude_users=[]):
-    role_users=[]
-    for user,details in users.iteritems():
+
+def extract_role_users(users={}, exclude_users=[]):
+    role_users = []
+    for user, details in users.items():
         if user not in exclude_users and "roles" in details:
             for role in details["roles"]:
-                role_users.append(role+":"+user)
+                role_users.append(role + ":" + user)
     return role_users
 
-def filename(filename=''):
+
+def filename(filename=""):
     return os.path.splitext(os.path.basename(filename))[0]
 
+
 def remove_reserved(user_roles={}):
     not_reserved = []
-    for user_role,details in user_roles.items():
-        if not "metadata" in details or not "_reserved" in details["metadata"] or not details["metadata"]["_reserved"]:
+    for user_role, details in user_roles.items():
+        if (
+            not "metadata" in details
+            or not "_reserved" in details["metadata"]
+            or not details["metadata"]["_reserved"]
+        ):
             not_reserved.append(user_role)
     return not_reserved
 
+
 def filter_reserved(users_role={}):
     reserved = []
-    for user_role,details in users_role.items():
-        if "metadata" in details and "_reserved" in details["metadata"] and details["metadata"]["_reserved"]:
+    for user_role, details in users_role.items():
+        if (
+            "metadata" in details
+            and "_reserved" in details["metadata"]
+            and details["metadata"]["_reserved"]
+        ):
             reserved.append(user_role)
     return reserved
 
+
 class FilterModule(object):
     def filters(self):
-        return {'modify_list': modify_list,
-        'append_to_list':append_to_list,
-        'filter_reserved':filter_reserved,
-        'array_to_str':array_to_str,
-        'extract_role_users':extract_role_users,
-        'remove_reserved':remove_reserved,
-        'filename':filename}
\ No newline at end of file
+        return {
+            "modify_list": modify_list,
+            "append_to_list": append_to_list,
+            "filter_reserved": filter_reserved,
+            "array_to_str": array_to_str,
+            "extract_role_users": extract_role_users,
+            "remove_reserved": remove_reserved,
+            "filename": filename,
+        }