old_contents: from devicehive.handlers.handler import Handler
  from devicehive.api import Api
  from devicehive.api_event import ApiEvent
  from devicehive.command import Command
  from devicehive.notification import Notification
  
  
  class ApiHandler(Handler):
      """Api handler class."""
  
      EVENT_COMMAND_INSERT_ACTION = 'command/insert'
      EVENT_COMMAND_UPDATE_ACTION = 'command/update'
      EVENT_COMMAND_KEY = 'command'
      EVENT_NOTIFICATION_ACTION = 'notification/insert'
      EVENT_NOTIFICATION_KEY = 'notification'
  
      def __init__(self, transport, auth, handler_class, handler_args,
                   handler_kwargs):
          Handler.__init__(self, transport)
          self._api = Api(self._transport, auth)
          self._handler = handler_class(self._api, *handler_args,
                                        **handler_kwargs)
          self._handle_connect = False
  
      def handle_connect(self):
          self._api.token.auth()
          self._api.server_timestamp = self._api.get_info()['server_timestamp']
          if not self._handle_connect:
              self._handler.handle_connect()
              self._handle_connect = True
  
      def handle_event(self, event):
          api_event = ApiEvent(event)
          action = api_event.action
          subscription_id = api_event.subscription_id
          if self._api.removed_subscription_id_exists(action, subscription_id):
              return
          event = api_event.event
          if action == self.EVENT_COMMAND_INSERT_ACTION:
              command = Command(self._api, event[self.EVENT_COMMAND_KEY])
              return self._handler.handle_command_insert(command)
          if action == self.EVENT_COMMAND_UPDATE_ACTION:
              command = Command(self._api, event[self.EVENT_COMMAND_KEY])
              return self._handler.handle_command_update(command)
          if action == self.EVENT_NOTIFICATION_ACTION:
              notification = Notification(event[self.EVENT_NOTIFICATION_KEY])
              return self._handler.handle_notification(notification)
  
      def handle_disconnect(self):
          # TODO: handle disconnect here.
          pass
  
new_contents: from devicehive.handlers.handler import Handler
  from devicehive.api import Api
  from devicehive.api_event import ApiEvent
  from devicehive.command import Command
  from devicehive.notification import Notification
  
  
  class ApiHandler(Handler):
      """Api handler class."""
  
      EVENT_COMMAND_INSERT_ACTION = 'command/insert'
      EVENT_COMMAND_UPDATE_ACTION = 'command/update'
      EVENT_COMMAND_KEY = 'command'
      EVENT_NOTIFICATION_ACTION = 'notification/insert'
      EVENT_NOTIFICATION_KEY = 'notification'
  
      def __init__(self, transport, auth, handler_class, handler_args,
                   handler_kwargs):
          Handler.__init__(self, transport)
          self._api = Api(self._transport, auth)
          self._handler = handler_class(self._api, *handler_args,
                                        **handler_kwargs)
          self._handle_connect = False
  
      @property
      def handler(self):
          return self._handler
  
      def handle_connect(self):
          self._api.token.auth()
          self._api.server_timestamp = self._api.get_info()['server_timestamp']
          if not self._handle_connect:
              self._handler.handle_connect()
              self._handle_connect = True
  
      def handle_event(self, event):
          api_event = ApiEvent(event)
          action = api_event.action
          subscription_id = api_event.subscription_id
          if self._api.removed_subscription_id_exists(action, subscription_id):
              return
          event = api_event.event
          if action == self.EVENT_COMMAND_INSERT_ACTION:
              command = Command(self._api, event[self.EVENT_COMMAND_KEY])
              return self._handler.handle_command_insert(command)
          if action == self.EVENT_COMMAND_UPDATE_ACTION:
              command = Command(self._api, event[self.EVENT_COMMAND_KEY])
              return self._handler.handle_command_update(command)
          if action == self.EVENT_NOTIFICATION_ACTION:
              notification = Notification(event[self.EVENT_NOTIFICATION_KEY])
              return self._handler.handle_notification(notification)
  
      def handle_disconnect(self):
          pass
  
subject: Add handler property