var stage = acgraph.create('container');
var simpleLayer = new acgraph.vector.Layer();
var elementStar = simpleLayer.star7(55, 79, 45);
elementStar.fill('#F44336');
simpleLayer.ellipse(85, 80, 35, 55);
simpleLayer.rect(55, 79, 75, 45);
var index = simpleLayer.indexOfChild(elementStar);
var element = simpleLayer.getChildAt(index);