protected function _payload()
    {
        $results = array();
        foreach( $this->Parameters as $key => $val )
        {
            if ( is_array( $val ) )
            {
                foreach ( $val as $vkey => $vval )
                {
                    $results[] = urlencode( $key ) . '[' . urlencode( $vkey ) . ']=' . urlencode( $vval );
                }
            }
            else
            {
                $results[] = urlencode( $key ) . '=' . urlencode( $val );
            }
        }
        return implode( '&', $results );
    }