private function get_defaults() {
    $defaults = array(
      'oauth_version'          => $this->config['oauth_version'],
      'oauth_nonce'            => $this->config['nonce'],
      'oauth_timestamp'        => $this->config['timestamp'],
      'oauth_consumer_key'     => $this->config['consumer_key'],
      'oauth_signature_method' => $this->config['oauth_signature_method'],
    );

    // include the user token if it exists
    if ( $this->config['user_token'] )
      $defaults['oauth_token'] = $this->config['user_token'];

    // safely encode
    foreach ($defaults as $k => $v) {
      $_defaults[$this->safe_encode($k)] = $this->safe_encode($v);
    }

    return $_defaults;
  }