docs: function relaxRightToLeft(nodesByBreadth, alpha, orient) {
      zrUtil.each(nodesByBreadth.slice().reverse(), function (nodes) {
          zrUtil.each(nodes, function (node) {
              if (node.outEdges.length) {
                  var y = sum(node.outEdges, weightedTarget, orient)
                          / sum(node.outEdges, getEdgeValue, orient);
                  if (orient === 'vertical') {
                      var nodeX = node.getLayout().x + (y - center(node, orient)) * alpha;
                      node.setLayout({x: nodeX}, true);
                  }
                  else {
                      var nodeY = node.getLayout().y + (y - center(node, orient)) * alpha;
                      node.setLayout({y: nodeY}, true);
                  }
              }
          });
      });
  }