code: function setTile(x, y, tileId) {
           if (!this.tileset.contains(tileId)) {
             // look for the corresponding tileset
             this.tileset = this.tilesets.getTilesetByGid(tileId);
           }
  
           var tile = this.layerData[x][y] = new me.Tile(x, y, tileId, this.tileset); // draw the corresponding tile
  
           if (this.preRender) {
             this.renderer.drawTile(this.canvasRenderer, x, y, tile);
           }
  
           return tile;
         }
docs: Create a new Tile at the specified position
  @name setTile
  @memberOf me.TMXLayer
  @public
  @function
  @param {Number} x X coordinate (in map coordinates: row/column)
  @param {Number} y Y coordinate (in map coordinates: row/column)
  @param {Number} tileId tileId
  @return {me.Tile} the corresponding newly created tile object