PubSub/src/Subscription.php
public function seekToTime(Timestamp $timestamp)
    {
        return $this->connection->seek([
            'subscription' => $this->name,
            'time' => $timestamp->formatAsString()
        ]);
    }
public function seekToTime(Timestamp $timestamp)
    {
        return $this->connection->seek([
            'subscription' => $this->name,
            'time' => $timestamp->formatAsString()
        ]);
    }
public function seekToTime ( Timestamp $ timestamp ) { return $ this -> connection -> seek ( [ 'subscription' => $ this -> name , 'time' => $ timestamp -> formatAsString ( ) ] ) ; }
Seek to a given timestamp.

When you seek to a time, it has the effect of marking every message
received before this time as acknowledged, and all messages received
after the time as unacknowledged.

Please note that this method may not yet be available in your project.

Example:
```
$time = $pubsub->timestamp(new \DateTime('2017-04-01'));
$subscription->seekToTime($time);
```

@param Timestamp $timestamp The time to seek to.
@return void
Seek to a given timestamp .