src/Utils.php
public static function getRefererQueryParam($url, $key)
    {
        if (!$url) {
            return null;
        }

        $query = [];

        parse_str(parse_url($url, PHP_URL_QUERY), $query);
        if (isset($query[$key])) {
            return $query[$key];
        }

        return null;
    }
public static function getRefererQueryParam($url, $key)
    {
        if (!$url) {
            return null;
        }

        $query = [];

        parse_str(parse_url($url, PHP_URL_QUERY), $query);
        if (isset($query[$key])) {
            return $query[$key];
        }

        return null;
    }
Searches the url for a query parameter of a given key.
@param string $url
@param string $key
@return mixed