    def _get_vector_tile(self, x_tile, y_tile, z_tile):
        """Load up a single vector tile."""
        cache_file = "mapscache/{}.{}.{}.json".format(z_tile, x_tile, y_tile)
        if cache_file not in self._tiles:
            if os.path.isfile(cache_file):
                with open(cache_file, 'rb') as f:
                    tile = json.loads(f.read().decode('utf-8'))
            else:
                url = _VECTOR_URL.format(z_tile, x_tile, y_tile, _KEY)
                data = requests.get(url).content
                try:
                    tile = mapbox_vector_tile.decode(data)
                    with open(cache_file, mode='w') as f:
                        json.dump(literal_eval(repr(tile)), f)
                except DecodeError:
                    tile = None
            if tile:
                self._tiles[cache_file] = [x_tile, y_tile, z_tile, tile, False]
                if len(self._tiles) > _CACHE_SIZE:
                    self._tiles.popitem(False)
                self._screen.force_update()
Load up a single vector tile.
samples/maps.py