diff --git a/lib/event_notification.py b/lib/event_notification.py
index 363caf4..53c010e 100755
--- a/lib/event_notification.py
+++ b/lib/event_notification.py
@@ -1,14 +1,15 @@
 #!/usr/bin/env python3
 
-import requests
-import websocket
 import json
 import ssl
-import gen_valid as gv
+
 import gen_print as gp
+import gen_valid as gv
+import requests
+import websocket
 
 
-class event_notification():
+class event_notification:
     r"""
     Main class to subscribe and receive event notifications.
     """
@@ -36,20 +37,22 @@
         r"""
         Login and return session object.
         """
-        http_header = {'Content-Type': 'application/json'}
+        http_header = {"Content-Type": "application/json"}
         session = requests.session()
-        response = session.post('https://' + self.__host + '/login',
-                                headers=http_header,
-                                json={"data": [self.__user, self.__password]},
-                                verify=False, timeout=30)
+        response = session.post(
+            "https://" + self.__host + "/login",
+            headers=http_header,
+            json={"data": [self.__user, self.__password]},
+            verify=False,
+            timeout=30,
+        )
         gv.valid_value(response.status_code, valid_values=[200])
         login_response = json.loads(response.text)
         gp.qprint_var(login_response)
-        gv.valid_value(login_response['status'], valid_values=['ok'])
+        gv.valid_value(login_response["status"], valid_values=["ok"])
         return session
 
     def subscribe(self, dbus_path, enable_trace=False):
-
         r"""
         Subscribe to the given path and return a list of event notifications.
 
@@ -79,15 +82,21 @@
         cookies = session.cookies.get_dict()
         # Convert from dictionary to a string of the following format:
         # key=value;key=value...
-        cookies = gp.sprint_var(cookies, fmt=gp.no_header() | gp.strip_brackets(),
-                                col1_width=0, trailing_char="",
-                                delim="=").replace("\n", ";")
+        cookies = gp.sprint_var(
+            cookies,
+            fmt=gp.no_header() | gp.strip_brackets(),
+            col1_width=0,
+            trailing_char="",
+            delim="=",
+        ).replace("\n", ";")
 
         websocket.enableTrace(enable_trace)
-        self.__websocket = websocket.create_connection("wss://{host}/subscribe".format(host=self.__host),
-                                                       sslopt={"cert_reqs": ssl.CERT_NONE},
-                                                       cookie=cookies)
-        dbus_path = [path.strip() for path in dbus_path.split(',')]
+        self.__websocket = websocket.create_connection(
+            "wss://{host}/subscribe".format(host=self.__host),
+            sslopt={"cert_reqs": ssl.CERT_NONE},
+            cookie=cookies,
+        )
+        dbus_path = [path.strip() for path in dbus_path.split(",")]
         dbus_path = {"paths": dbus_path}
 
         self.__websocket.send(json.dumps(dbus_path))