44     private $expiration;  variable in Google\\Auth\\Cache\\Item
84         if ($this->expiration === null) {
88         return $this->currentTime()->getTimestamp() < $this->expiration->getTimestamp();
105     public function expiresAt($expiration)  argument
107         if ($this->isValidExpiration($expiration)) {
108             $this->expiration = $expiration;
116             gettype($expiration)
128             $this->expiration = $this->currentTime()->add(new \DateInterval("PT{$time}S"));
130             $this->expiration = $this->currentTime()->add($time);
132             $this->expiration = $time;
147      * @param mixed $expiration
150     private function isValidExpiration($expiration)  argument
152         if ($expiration === null) {
156         if ($expiration instanceof DateTimeInterface) {