code: def get_default_dashboard(self):
          
          if self.default_dashboard:
              return self._registered(self.default_dashboard)
          elif self._registry:
              return self.get_dashboards()[0]
          else:
              raise NotRegistered("No dashboard modules have been registered.")
docs: Returns the default :class:`~horizon.Dashboard` instance.
  
          If ``"default_dashboard"`` is specified in ``HORIZON_CONFIG``
          then that dashboard will be returned. If not, the first dashboard
          returned by :func:`~horizon.get_dashboards` will be returned.