class MapStepRegistry implements StepRegistry {

	private final ConcurrentMap<String, Map<String, Step>> map = new ConcurrentHashMap<>();

	@Override
	public void register(String jobName, Collection<Step> steps) throws DuplicateJobException {
		Assert.notNull(jobName, "The job name cannot be null.");
		Assert.notNull(steps, "The job steps cannot be null.");

		final Map<String, Step> jobSteps = new HashMap<>();
		for (Step step : steps) {
			jobSteps.put(step.getName(), step);
		}
		final Object previousValue = map.putIfAbsent(jobName, jobSteps);
		if (previousValue != null) {
			throw new DuplicateJobException(
					"A job configuration with this name [" + jobName + "] was already registered");
		}
	}

	@Override
	public void unregisterStepsFromJob(String jobName) {
		Assert.notNull(jobName, "Job configuration must have a name.");
		map.remove(jobName);
	}

	@Override
	public Step getStep(String jobName, String stepName) throws NoSuchJobException {<FILL_FUNCTION_BODY>}

}

		Assert.notNull(jobName, "The job name cannot be null.");
		Assert.notNull(stepName, "The step name cannot be null.");
		if (!map.containsKey(jobName)) {
			throw new NoSuchJobException("No job configuration with the name [" + jobName + "] was registered");
		}
		else {
			final Map<String, Step> jobSteps = map.get(jobName);
			if (jobSteps.containsKey(stepName)) {
				return jobSteps.get(stepName);
			}
			else {
				throw new NoSuchStepException(
						"The step called [" + stepName + "] does not exist in the job [" + jobName + "]");
			}
		}
	
<no_super_class>