code: @Override
      public DescribeStepResult describeStep(DescribeStepRequest request) {
          request = beforeClientExecution(request);
          return executeDescribeStep(request);
      }
docs: <p>
  Provides more detail about the cluster step.
  </p>
  
  @param describeStepRequest
  This input determines which step to describe.
  @return Result of the DescribeStep operation returned by the service.
  @throws InternalServerException
  This exception occurs when there is an internal failure in the EMR service.
  @throws InvalidRequestException
  This exception occurs when there is something wrong with user input.
  @sample AmazonElasticMapReduce.DescribeStep
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/elasticmapreduce-2009-03-31/DescribeStep" target="_top">AWS
  API Documentation</a>