code: function computeEdgeDepths(nodes, orient) {
      var keyAttr = orient === 'vertical' ? 'x' : 'y';
      zrUtil.each(nodes, function (node) {
          node.outEdges.sort(function (a, b) {
              return a.node2.getLayout()[keyAttr] - b.node2.getLayout()[keyAttr];
          });
          node.inEdges.sort(function (a, b) {
              return a.node1.getLayout()[keyAttr] - b.node1.getLayout()[keyAttr];
          });
      });
      zrUtil.each(nodes, function (node) {
          var sy = 0;
          var ty = 0;
          zrUtil.each(node.outEdges, function (edge) {
              edge.setLayout({sy: sy}, true);
              sy += edge.getLayout().dy;
          });
          zrUtil.each(node.inEdges, function (edge) {
              edge.setLayout({ty: ty}, true);
              ty += edge.getLayout().dy;
          });
      });
  }
docs: Compute the depth(y-position) of each edge
  
  @param {module:echarts/data/Graph~Node} nodes  node of sankey view