docs: def _build_from_geojson(self, src):
          """ Build a RTree index to disk using bounding box of each feature """
          geojson = json.loads(self.read(src))
          idx = index.Index()
          data_store = {}
          for i, feature in enumerate(geojson['features']):
              feature = self._build_obj(feature)
              idx.insert(i, feature['geometry'].bounds)
              data_store[i] = feature
          return data_store, idx