code: function(options) {
          options = options || {};
          L.Util.setOptions(this, options);
          this._layers = {};
          this._columns = this.options.columns || [];
          this.options.imageOptions = this.options.imageOptions || {};
          this.options.sheetNum = this.options.sheetNum || 0;
          this._parsedToOrig = {};
          this._lat = this._cleanColumnName(this.options.lat);
          this._lon = this._cleanColumnName(this.options.lon);
          this._columns = this._cleanColumns(this._columns);
      }
docs: Optional: imageOptions: defaults to blank sheet index: defaults to 0 (first sheet) },