var invertTree = function (root) {
if (root !== null) {
[root.left, root.right] = [root.right, root.left]
invertTree(root.left)
invertTree(root.right)
}
return root
}
var invertTree = function (root) {
if (root !== null) {
[root.left, root.right] = [root.right, root.left]
invertTree(root.left)
invertTree(root.right)
}
return root
}