private function get_installation_token()
 {
     $is_token_valid = false;
     try {
         $is_token_valid = $this->token->exists() && $this->token->read() == self::$token_file_content;
     } catch (IOException $ioe) {
         $is_token_valid = false;
     }
     if (!$is_token_valid) {
         throw new TokenNotFoundException($this->token->get_path_from_root());
     }
 }