public int countTileNum (Extent extent, int tileSize) { int diff = extent.toInt();
public int countTileNum(Address start, Address end, int tileSize) { if (end.LE(start)) return 0; int diff = end.diff(start).toInt();
  public int countTileNum (Extent extent, int tileSize) {    int diff = extent.toInt();    return countTileNum(diff, tileSize);  }