title: query dynamodb with BETWEEN ComparisonOperator
body: <p>In DynamoDB I would like to make a query using the <code>BETWEEN</code> ComparisonOperator, but I am getting stuck on the syntax.</p>
  
  <p>From what I could find this should be how it is done:</p>
  
  <pre><code>$iterator = $client-&gt;query(array(
    'TableName' =&gt; 'test',
    'IndexName' =&gt; 'lft-index',
    'KeyConditions' =&gt; array(
      'lft' =&gt; array(
        'AttributeValueList' =&gt; array(
          array(
            'N' =&gt; 15
          ),
          array(
              'N' =&gt; 18),
        ),
        'ComparisonOperator' =&gt; 'BETWEEN',
      ),
    ),
  ));
  </code></pre>
  
  <p>With this code, I get the error message: AWS Error Message: Query key condition not supported</p>