code: @Override
      public DescribeStackInstanceResult describeStackInstance(DescribeStackInstanceRequest request) {
          request = beforeClientExecution(request);
          return executeDescribeStackInstance(request);
      }
docs: <p>
  Returns the stack instance that's associated with the specified stack set, AWS account, and region.
  </p>
  <p>
  For a list of stack instances that are associated with a specific stack set, use <a>ListStackInstances</a>.
  </p>
  
  @param describeStackInstanceRequest
  @return Result of the DescribeStackInstance operation returned by the service.
  @throws StackSetNotFoundException
  The specified stack set doesn't exist.
  @throws StackInstanceNotFoundException
  The specified stack instance doesn't exist.
  @sample AmazonCloudFormation.DescribeStackInstance
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/cloudformation-2010-05-15/DescribeStackInstance"
  target="_top">AWS API Documentation</a>