class TileList {

    public T getItemAt(int pos) {
        if (mLastAccessedTile == null || !mLastAccessedTile.containsPosition(pos)) {
            final int startPosition = pos - (pos % mTileSize);
            final int index = mTiles.indexOfKey(startPosition);
            if (index < 0) {
                return null;
            }
            mLastAccessedTile = mTiles.valueAt(index);
        }
        return mLastAccessedTile.getByPosition(pos);
    }

    public  TileList(int tileSize);

}