function postOrder(root) {
	  let result = []
		let values = ""
    
    function dfsPostTraverse(currentNode){
        if(currentNode == null){
            return;
        }
        dfsPostTraverse(currentNode.left)
        dfsPostTraverse(currentNode.right)
        result.push(currentNode.data)
    }
    
    dfsPostTraverse(root)
    
    for(let i=0; i<result.length; i++){
        values += result[i] + " "
    }
    console.log(values)
}