src/data/Tree.js
function addChild(child, node) {
    var children = node.children;
    if (child.parentNode === node) {
        return;
    }

    children.push(child);
    child.parentNode = node;
}
function addChild(child, node) {
    var children = node.children;
    if (child.parentNode === node) {
        return;
    }

    children.push(child);
    child.parentNode = node;
}
function addChild ( child , node ) { var children = node . children ; if ( child . parentNode === node ) { return ; } children . push ( child ) ; child . parentNode = node ; }
It is needed to consider the mess of 'list', 'hostModel' when creating a TreeNote,
so this function is not ready and not necessary to be public.

@param {(module:echarts/data/Tree~TreeNode|Object)} child
It is needed to consider the mess of list hostModel when creating a TreeNote so this function is not ready and not necessary to be public .