code: public Tile getAboveLeft() {
          int y = tileY - 1;
          int x = tileX - 1;
          if (y < 0) {
              y = getMaxTileNumber(this.zoomLevel);
          }
          if (x < 0) {
              x = getMaxTileNumber(this.zoomLevel);
          }
          return new Tile(x, y, this.zoomLevel, this.tileSize);
      }
docs: Returns the tile above left
  
  @return tile above left