private boolean is_in(Vector<Identifier> parent, Vector<Identifier> child) {
            int pi = 0;
            int ci = 0;
            while (true){
                if (parent.get(pi).equals(child.get(ci))) {
                    ci++;
                    pi++;
                }else {
                    pi++;
                }
                if (ci == child.size()){
                    return true;
                }
                if (pi == parent.size()){
                    return false;
                }
            }
        }