function getEdgeShape(seriesScope, sourceLayout, targetLayout) {
    var cpx1;
    var cpy1;
    var cpx2;
    var cpy2;
    var orient = seriesScope.orient;
    var x1;
    var x2;
    var y1;
    var y2;

    if (seriesScope.layout === 'radial') {
        x1 = sourceLayout.rawX;
        y1 = sourceLayout.rawY;
        x2 = targetLayout.rawX;
        y2 = targetLayout.rawY;

        var radialCoor1 = radialCoordinate(x1, y1);
        var radialCoor2 = radialCoordinate(x1, y1 + (y2 - y1) * seriesScope.curvature);
        var radialCoor3 = radialCoordinate(x2, y2 + (y1 - y2) * seriesScope.curvature);
        var radialCoor4 = radialCoordinate(x2, y2);

        return {
            x1: radialCoor1.x,
            y1: radialCoor1.y,
            x2: radialCoor4.x,
            y2: radialCoor4.y,
            cpx1: radialCoor2.x,
            cpy1: radialCoor2.y,
            cpx2: radialCoor3.x,
            cpy2: radialCoor3.y
        };
    }
    else {
        x1 = sourceLayout.x;
        y1 = sourceLayout.y;
        x2 = targetLayout.x;
        y2 = targetLayout.y;

        if (orient === 'LR' || orient === 'RL') {
            cpx1 = x1 + (x2 - x1) * seriesScope.curvature;
            cpy1 = y1;
            cpx2 = x2 + (x1 - x2) * seriesScope.curvature;
            cpy2 = y2;
        }
        if (orient === 'TB' || orient === 'BT') {
            cpx1 = x1;
            cpy1 = y1 + (y2 - y1) * seriesScope.curvature;
            cpx2 = x2;
            cpy2 = y2 + (y1 - y2) * seriesScope.curvature;
        }
    }

    return {
        x1: x1,
        y1: y1,
        x2: x2,
        y2: y2,
        cpx1: cpx1,
        cpy1: cpy1,
        cpx2: cpx2,
        cpy2: cpy2
    };

}
Traverse the tree from top to bottom and do something
@param  {module:echarts/data/Tree~TreeNode} root  The real root of the tree
@param  {Function} callback