Integrate ABC module where we have abstract classes

lib/tfw/event_handler_base.py

@@ -1,8 +1,10 @@
+from abc import ABC, abstractmethod
+
 from tfw.networking.serialization import deserialize_all
 from tfw.networking.event_handlers.server_connector import ServerConnector
 
 
-class EventHandlerBase:
+class EventHandlerBase(ABC):
     def __init__(self, key):
         self.server_connector = ServerConnector()
         self.key = key
@@ -17,6 +19,7 @@ class EventHandlerBase:
         if response is None: return
         self.server_connector.send(key, response)
 
+    @abstractmethod
     def dispatch_handling(self, key, message):
         raise NotImplementedError
 
@@ -24,6 +27,7 @@ class EventHandlerBase:
         if key != 'reset': return self.handle_event(key, message)
         else: return self.handle_reset(message)
 
+    @abstractmethod
     def handle_event(self, key, message):
         raise NotImplementedError
 
@@ -58,12 +62,12 @@ class EventHandlerBase:
         self.subscriptions.clear()
 
 
-class TriggerlessEventHandler(EventHandlerBase):
+class TriggerlessEventHandler(EventHandlerBase, ABC):
     def dispatch_handling(self, key, message):
         return self._dispatch_handling(key, message)
 
 
-class TriggeredEventHandler(EventHandlerBase):
+class TriggeredEventHandler(EventHandlerBase, ABC):
     def __init__(self, key, trigger):
         super().__init__(key)
         self.trigger = trigger

lib/tfw/networking/server/zmq_websocket_handler.py

@@ -1,4 +1,5 @@
 import json
+from abc import ABC, abstractmethod
 
 from tornado.websocket import WebSocketHandler
 
@@ -9,7 +10,7 @@ from tfw.config.logs import logging
 LOG = logging.getLogger(__name__)
 
 
-class ZMQWebSocketHandler(WebSocketHandler):
+class ZMQWebSocketHandler(WebSocketHandler, ABC):
     _event_handler_connector = EventHandlerConnector()
     instances = set()
 
@@ -45,6 +46,7 @@ class ZMQWebSocketHandler(WebSocketHandler):
         LOG.debug('Received on WebSocket: %s', message)
         self.send_message(self.make_response(message))
 
+    @abstractmethod
     def make_response(self, message):
         raise NotImplementedError