Make spreadsheet editable for visitors

Hi guys, I want to make this spreadshit editable even for visitor in my web site. I just dont know where to change this role.
I tried to do this:

$available_to = Array(
‘administrator’ => true,
‘editor’ => true,
‘author’ => true,
‘visitor’ => true

But its not working.Here is the original code:

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error_reporting(0);
require_once(‘../../../wp-config.php’);
define(‘WP_USE_THEMES’, true);
require_once(“./codebase/php/grid_cell_connector.php”);

$res = mysql_connect(DB_HOST, DB_USER, DB_PASSWORD);
mysql_select_db(DB_NAME, $res);

get_currentuserinfo();
if (isset($current_user->roles[0])) {
$usertype = $current_user->roles[0];
} else {
$usertype = ‘guest’;
}

$available_to = Array(
‘administrator’ => true,
‘editor’ => true,
‘author’ => true

);

$conn = new GridCellConnector($res, $table_prefix.”dhx_”);
if (!isset($available_to[$usertype]) || $available_to[$usertype] == false)
$conn->set_read_only(true);
$conn->render();

?>
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