code: def find_donor_catchments(self, limit=6, dist_limit=500):
          
          if self.gauged_catchments:
              return self.gauged_catchments.nearest_qmed_catchments(self.catchment, limit, dist_limit)
          else:
              return []
docs: Return a suitable donor catchment to improve a QMED estimate based on catchment descriptors alone.
  
          :param limit: maximum number of catchments to return. Default: 6. Set to `None` to return all available
                        catchments.
          :type limit: int
          :param dist_limit: maximum distance in km. between subject and donor catchment. Default: 500 km. Increasing the
                             maximum distance will increase computation time!
          :type dist_limit: float or int
          :return: list of nearby catchments
          :rtype: :class:`floodestimation.entities.Catchment`