code: function pointToTile(lon, lat, z) {
      var tile = pointToTileFraction(lon, lat, z);
      tile[0] = Math.floor(tile[0]);
      tile[1] = Math.floor(tile[1]);
      return tile;
  }
docs: Get the tile for a point at a specified zoom level
  
  @name pointToTile
  @param {number} lon
  @param {number} lat
  @param {number} z
  @returns {Array<number>} tile
  @example
  var tile = pointToTile(1, 1, 20)
  //=tile