public String[] subexpressoes(String expressao){
        String retorno[] = new String[nrSubexpressoes(expressao)];
        retorno[0] = expressao;
        int k = expressao.lastIndexOf('(');
        int v = expressao.indexOf(')');
        String temp, temp2;
        for(int i = 1; i<=nrSubexpressoes(expressao);i++){
            temp = expressao.substring(k, v);
            retorno[i] = temp;
            temp = expressao.substring(0, k);
            k = expressao.lastIndexOf('(');
            v = expressao.indexOf(')',v);
        }



        return null;
    }