public void loadTree(String datum) {//this works for postfix
        for (int i=0;i<datum.length();i++) { //*NOTE* this dumps whatever is in memory already each time it is called
           if ((datum.charAt(i) >='a' && datum.charAt(i)<='z') ||
                   (datum.charAt(i) >= 'A' && datum.charAt(i) <= 'Z')) {
               theStack.push(new Leaf(datum.charAt(i)));
           }//end if
            else {//assuming clean inputs
               Leaf temp = new Leaf(datum.charAt(i));
               temp.right=theStack.pop();
               temp.left=theStack.pop();
               theStack.push(temp);
           }//end else
        }//end for
        root=theStack.pop();
    }