code: def logout(current):
      
      current.user.is_online(False)
      current.session.delete()
      current.output['cmd'] = 'logout'
      if current.task_data.get('show_logout_message', False):
          current.output['title'] = current.task_data.get('logout_title', None)
          current.output['msg'] = current.task_data.get('logout_message', None)
docs: Log out view.
      Simply deletes the session object.
      For showing logout message:
          'show_logout_message' field should be True in current.task_data,
          Message should be sent in current.task_data with 'logout_message' field.
          Message title should be sent in current.task_data with 'logout_title' field.
  
          current.task_data['show_logout_message'] = True
          current.task_data['logout_title'] = 'Message Title'
          current.task_data['logout_message'] = 'Message'
  
      Args:
          current: :attr:`~zengine.engine.WFCurrent` object.