public void DoWork( WorkOrder workOrder ) {
	this.WorkOrder = workOrder ?? throw new System.ArgumentNullException( "workOrder" );
	var steps = ( this.Steps ?? new IStep[ 0 ] ).OfType<IStep>();
	if ( !steps.Any() ) {
		return;
	}
	using ( var tokenSource = new System.Threading.CancellationTokenSource() ) {
		var token = tokenSource.Token;
		var maxP = this.MaxDegreeOfParallelism;
		if ( DefaultMaxDegreeOfParallelism == maxP ) {
			this.DoUnlimitedWork( workOrder, steps, token );
		} else {
			this.DoLimitedWork( workOrder, steps, token, maxP );
		}
	}
}
private void DoUnlimitedWork( WorkOrder workOrder, System.Collections.Generic.IEnumerable<IStep> steps, System.Threading.CancellationToken token ) {
	System.Collections.Generic.ICollection<System.Threading.Tasks.Task> tasks = new System.Collections.Generic.List<System.Threading.Tasks.Task>();
	var factory = new System.Threading.Tasks.TaskFactory(
		token,
		System.Threading.Tasks.TaskCreationOptions.LongRunning,
		System.Threading.Tasks.TaskContinuationOptions.LongRunning,
		System.Threading.Tasks.TaskScheduler.Default
	);
	foreach ( var step in steps ) {
		tasks.Add( factory.StartNew(
			() => step.DoWork( workOrder ),
			token
		) );
	}
	System.Threading.Tasks.Task.WaitAll( tasks.ToArray(), token );
}
private void DoLimitedWork( WorkOrder workOrder, System.Collections.Generic.IEnumerable<IStep> steps, System.Threading.CancellationToken token, System.Int32 MaxDegreeOfParallelism ) {
	using ( var semaphore = new Semaphore( this.MaxDegreeOfParallelism, this.MaxDegreeOfParallelism ) ) {
		System.Collections.Generic.ICollection<System.Threading.Tasks.Task> tasks = new System.Collections.Generic.List<System.Threading.Tasks.Task>();
		var factory = new System.Threading.Tasks.TaskFactory( token );
		foreach ( var step in steps ) {
			tasks.Add( factory.StartNew(
				() => {
					semaphore.Wait();
					step.DoWork( workOrder );
					semaphore.Release();
				},
				token
			) );
		}
		System.Threading.Tasks.Task.WaitAll( tasks.ToArray(), token );
	}
}