public static function login()
 {
     $login = Core::validate(self::getVar('login'));
     $pass = Core::validate(self::getVar('pass'));
     $usr = new User();
     $userExistResult = $usr->isUserExist($login, Core::calculateHash($pass));
     if (!$userExistResult) {
         header("Location: /");
         return false;
     }
     $session = new Session();
     if ($session->isSessionExistByUserId($usr->getId())) {
         $session->delete();
     }
     $session->create($usr->getId(), Core::getClientIP());
     header('Location: /usr/mypage/');
 }