function quadtreeCoordinates(level, x, y, subtreeLevels) {
    return new ImplicitTileCoordinates({
      subdivisionScheme: ImplicitSubdivisionScheme.QUADTREE,
      subtreeLevels: subtreeLevels ?? 2,
      level: level,
      x: x,
      y: y,
    });
  }
Helper function for creating quadtree implicit tile coordinates
@param {number} level
@param {number} x
@param {number} y
@param {number} [subtreeLevels=2]
@returns {ImplicitTileCoordinates}