public Variable search(String name) {
        ListIterator<ArrayList<Variable>> blocks = stack.listIterator(stack.size());
        while(blocks.hasPrevious()) {
            ArrayList<Variable> block = blocks.previous();
            for(Variable v : block) {
                if( v.get_name().equals(name) ) {
                    return v;
                }
            }
        }
        return null;
    }



public Variable search_scope(String name, int _scope) {
        int diff;

        if(_scope > scope)
            return null;

        if(_scope == 0)
            diff = 0;
        else
            diff = scope - _scope;
        ArrayList<Variable> block = stack.elementAt(diff);
        for(Variable v : block) {
            if( v.get_name().equals(name) ) {
                return v;
            }
        }
        return null;
    }