private Deque<Object> OperatorTree(Queue<Object> rpn){
Deque<Object> operand = new LinkedList<Object>();
while(!rpn.isEmpty()){
if(rpn.peek() instanceof Operator){
Operator opt = (Operator) rpn.poll();
opt.wrap(operand);
operand.addFirst(opt);
continue;
}
if(rpn.peek() instanceof IdentifierObj){
((IdentifierObj) rpn.peek()).setEc(ec);