docs: def process(self, pq):
          """
          :arg PlaceQuery pq: PlaceQuery instance
          :returns: One of the three following values:
                     * unmodified PlaceQuery instance if pq.country is not empty
                     * PlaceQuery instance with pq.country changed to default country.
                     * ``False`` if pq.country is empty and self.default_country == ''.
          """
          if pq.country.strip() == '':
              if self.default_country == '':
                  return False
              else:
                  pq.country = self.default_country
          return pq