Adding New Currency

I have added this code to my theme function.php but still i did not find the currency at the list of currency on the theme. please help me out.

function add_adverts_currency($list) {

$list[] = array(
“code”=>”NGN”, // ISO 4217 currency code, see https://en.wikipedia.org/wiki/ISO_4217
“sign”=>”Naira”, // currency prefix or postfix
“label”=>”Nigerian Naira” // currency long name
);

return $list;
}