array session

i made a helper, then i keep use the ci_session, just to save a session multi array

function set_userdata_array($data, $new_value)
{
$CI = &get_instance();
if (isset($_SESSION[$data]))
{
/**
* to prevent same value
*/
$unique_values = array();

foreach ($CI->session->userdata($data) as $value)
{
if (!in_array($value, $unique_values))//check if already one
{
$unique_values[] = $value; //get the usinque value
}
}

if (!in_array($new_value, $unique_values))//check if already one
{
$unique_values[] = $new_value; //now append the new value
}

$CI->session->set_userdata($data, $unique_values); //replaca the value with additional one
}
else
{
$CI->session->set_userdata($data, array($new_value)); //just create new one the initialize the value.
}
}