function addEl(data, dataGroup, dataIndex, dimensions, coordSys) {
	        var points = createLinePoints(data, dataIndex, dimensions, coordSys);
	        var line = new graphic.Polyline({
	            shape: {points: points},
	            silent: true,
	            z2: 10
	        });
	        dataGroup.add(line);
	        data.setItemGraphicEl(dataIndex, line);
	    }
@private
@type {module:echarts/chart/sankey/SankeySeries}