Listing AWS S3 buckets using the PHP SDK

I'm using the PHP AWS SDK and would like to list all buckets available to me in S3.

I found a few different blocks of documentation that look promising:

• http://docs.aws.amazon.com/AWSSDKforPHP/latest/index.html#m=AmazonS3/get_bucket_list
• http://docs.aws.amazon.com/aws-sdk-php/latest/class-Aws.S3.Iterator.ListBucketsIterator.html

Here's what I'm trying, using the AWS Service Builder to initialize an S3 client...

use Aws\Common\Aws;

// Instantiate an S3 client
$aws = Aws::factory(array( 'key' => "MY_KEY", 'secret' => "MY_SECRET"));
$s3 = $aws->get('s3');
$s3->get_bucket_list();

Unfortunately when I run the code I am told that it has no freakin' clue what "get_buckets_list" is. More specifically it says

Fatal error: Uncaught exception 'Guzzle\Common\Exception\InvalidArgumentException' with message 'Command was not found matching GetBucketList' in vendor/guzzle/guzzle/src/Guzzle/Service/Client.php:87

So my questions are as follows:

• Am I looking at the wrong documentation?
• Is there other documentation somewhere?
• How do you get a list of buckets using the PHP AWS SDK?