code: def _autobounds(self):
          
          bounds = {}
  
          def check(prop, compare, extreme, val):
              opp = min if compare is max else max
              bounds.setdefault(prop, val)
              bounds[prop] = opp(compare(bounds[prop], val), extreme)
  
          def bound_check(lat_lon):
              lat, lon = lat_lon
              check('max_lat', max, 90, lat)
              check('min_lat', min, -90, lat)
              check('max_lon', max, 180, lon)
              check('min_lon', min, -180, lon)
  
          lat_lons = [lat_lon for feature in self._features.values() for
                      lat_lon in feature.lat_lons]
          if not lat_lons:
              lat_lons.append(self._default_lat_lon)
          for lat_lon in lat_lons:
              bound_check(lat_lon)
  
          return bounds
docs: Simple calculation for bounds.