diff --git a/lib/event_notification.py b/lib/event_notification.py
index 53c010e..dfc51ca 100755
--- a/lib/event_notification.py
+++ b/lib/event_notification.py
@@ -1,15 +1,19 @@
 #!/usr/bin/env python3
-
+r"""
+This is an extended user library to support Robot Selenium code.
+The class contains functions which the robot framework will use
+and import as a user-defined keyword.
+"""
 import json
 import ssl
 
-import gen_print as gp
-import gen_valid as gv
+import gen_print as gp  # NOQA
+import gen_valid as gv  # NOQA
 import requests
 import websocket
 
 
-class event_notification:
+class event_notification:  # NOQA
     r"""
     Main class to subscribe and receive event notifications.
     """
@@ -26,6 +30,7 @@
         self.__host = host
         self.__user = username
         self.__password = password
+        self.__websocket = None
 
     def __del__(self):
         try:
@@ -92,7 +97,7 @@
 
         websocket.enableTrace(enable_trace)
         self.__websocket = websocket.create_connection(
-            "wss://{host}/subscribe".format(host=self.__host),
+            f"wss://{self.__host}/subscribe",
             sslopt={"cert_reqs": ssl.CERT_NONE},
             cookie=cookies,
         )