code: public static int longitudeToTileX(double longitude, byte zoomLevel) {
          return pixelXToTileX(longitudeToPixelX(longitude, zoomLevel, DUMMY_TILE_SIZE), zoomLevel, DUMMY_TILE_SIZE);
      }
docs: Converts a longitude coordinate (in degrees) to the tile X number at a certain zoom level.
  
  @param longitude the longitude coordinate that should be converted.
  @param zoomLevel the zoom level at which the coordinate should be converted.
  @return the tile X number of the longitude value.