code: function Grid(cellSize, cellCount, parentHierarchy) {
      this.cellSize = cellSize;
      this.inverseCellSize = 1 / cellSize;
      this.rowColumnCount = ~~Math.sqrt(cellCount);
      this.xyHashMask = this.rowColumnCount - 1;
      this.occupiedCells = [];
      this.allCells = Array(this.rowColumnCount * this.rowColumnCount);
      this.allObjects = [];
      this.sharedInnerOffsets = [];
  
      this._parentHierarchy = parentHierarchy || null;
  }
docs: Grid
  
  @constructor
  @param    int cellSize  the pixel size of each cell of the grid
  @param    int cellCount  the total number of cells for the grid (width x height)
  @param    HSHG parentHierarchy    the HSHG to which this grid belongs
  @return  void