One of the higher-level abstractions provided by the SDK are **waiters**. Waiters help make it easier to work with
*eventually consistent* systems by providing an easy way to wait until a resource enters into a particular state by
polling the resource. You can find a list of the waiters supported by a client by viewing the docblock of a client. Any
``@method`` tag that has a name starting with "``waitUntil``" will utilize a waiter.

.. code-block:: php

    $client->waitUntilBucketExists(array('Bucket' => 'my-bucket'));

The preceding method invocation will instantiate a waiter object and poll the bucket until it exists.