Core_HttpIO::_key_string

protected static function _key_string($arr, $key)
{
    if (!is_array($arr))return null;
    if ($key === null || $key === false || !strlen($key) > 0)
    {
        return $arr;
    }
    $keyArr = explode('.', $key);
    foreach ($keyArr as $key)
    {
        if (is_array($arr) && isset($arr[$key]))
        {
            $arr = $arr[$key];
        }
        else
        {
            return null;
        }
    }
    return $arr;
}