private List<Tree<String>> readChildren() throws IOException {
        readWhiteSpace();
        List<Tree<String>> children = new ArrayList<Tree<String>>();
        Tree<String> child;
        while (!isRightParen(peek())){
            readWhiteSpace();
            if (!isLeftParen(peek())){
            	child = readLeaf();
            }
            else {
            	child = readTree();
            }
            children.add(child);
        }
        return children;
    }