function removeTileFromLookup(tilesByZ, tile, z) {
  const set = tilesByZ[z];
  if (set) {
    return set.delete(tile);
  }
  return false;
}
Remove a tile from the lookup.
@param {TileLookup} tilesByZ Lookup of tiles by zoom level.
@param {import("../../Tile.js").default} tile A tile.
@param {number} z The zoom level.
@return {boolean} The tile was removed from the lookup.