src/Storage/Session.php
public function has($uid) {
        if (null === $this->session) {
            return false;
        }
        return $this->session->offsetExists($uid);
    }
public function has($uid) {
        if (null === $this->session) {
            return false;
        }
        return $this->session->offsetExists($uid);
    }
Test if has datas with $uid key
@param mixed $uid
@return boolean