function _channelExists($channel, $noaliases = false)
    {
        $a = file_exists($this->_channelFileName($channel, $noaliases));
        if (!$a && $channel == 'pear.php.net') {
            return true;
        }

        if (!$a && $channel == 'pecl.php.net') {
            return true;
        }

        if (!$a && $channel == 'doc.php.net') {
            return true;
        }

        return $a;
    }