code: def get_tasks(self, backend):
          
          try:
              res = self.send_signal(backend, STATUS)
          except BackendNotAvailableError:
              res = 'down'
          return res
docs: Gets a string of the tasks running on `backend`. This string will 
          either be an integer if the backend is up, or else 'down'.Raises 
          ValueError if `backend` is not registered with the client.
          
          Example:
          
          >>> frontend = FrontEnd(['localhost', '****'])
          >>> frontend.get_tasks('localhost')
          '5'
          >>> frontend.get_tasks('****')
          'down'
          >>> frontend.get_tasks('unregistered')
          Traceback (most recent call last):
          [...]
          ValueError: No such backend!