/**
  * Describe Instances 
  * The DescribeInstances operation returns information about instances that you
  * own.
  * If you specify one or more instance IDs, Amazon EC2 returns information for
  * those instances. If you do not specify instance IDs, Amazon EC2 returns
  * information for all relevant instances. If you specify an invalid instance ID,
  * a fault is returned. If you specify an instance that you do not own, it will
  * not be included in the returned results.
  * Recently terminated instances might appear in the returned results. This
  * interval is usually less than one hour.
  * 
  * @see http://docs.amazonwebservices.com/AWSEC2/2008-12-01/DeveloperGuide/ApiReference-Query-DescribeInstances.html
  * @param mixed $request array of parameters for Amazon_EC2_Model_DescribeInstancesRequest request
  * or Amazon_EC2_Model_DescribeInstancesRequest object itself
  * @see Amazon_EC2_Model_DescribeInstances
  * @return Amazon_EC2_Model_DescribeInstancesResponse Amazon_EC2_Model_DescribeInstancesResponse
  *
  * @throws Amazon_EC2_Exception
  */
 public function describeInstances($request)
 {
     if (!$request instanceof Amazon_EC2_Model_DescribeInstancesRequest) {
         require_once 'Amazon/EC2/Model/DescribeInstancesRequest.php';
         $request = new Amazon_EC2_Model_DescribeInstancesRequest($request);
     }
     require_once 'Amazon/EC2/Model/DescribeInstancesResponse.php';
     return Amazon_EC2_Model_DescribeInstancesResponse::fromXML($this->_invoke($this->_convertDescribeInstances($request)));
 }
 /**
  * Describe Instances 
  * The DescribeInstances operation returns information about instances that you
  * own.
  * If you specify one or more instance IDs, Amazon EC2 returns information for
  * those instances. If you do not specify instance IDs, Amazon EC2 returns
  * information for all relevant instances. If you specify an invalid instance ID,
  * a fault is returned. If you specify an instance that you do not own, it will
  * not be included in the returned results.
  * Recently terminated instances might appear in the returned results. This
  * interval is usually less than one hour.
  *   
  * @see http://docs.amazonwebservices.com/AWSEC2/2008-12-01/DeveloperGuide/ApiReference-Query-DescribeInstances.html      
  * @param mixed $request array of parameters for Amazon_EC2_Model_DescribeInstances request or Amazon_EC2_Model_DescribeInstances object itself
  * @see Amazon_EC2_Model_DescribeInstances
  * @return Amazon_EC2_Model_DescribeInstancesResponse Amazon_EC2_Model_DescribeInstancesResponse
  *
  * @throws Amazon_EC2_Exception
  */
 public function describeInstances($request)
 {
     require_once 'Amazon/EC2/Model/DescribeInstancesResponse.php';
     return Amazon_EC2_Model_DescribeInstancesResponse::fromXML($this->_invoke('DescribeInstances'));
 }