error CS0103: The name 'ModelHelper' does not exist in the current context - object-detection

Question

I am trying to implement Object detection on HoloLens2 using Microsoft Custom Vision.
I have been following the tutorial (https://learn.microsoft.com/en-us/archive/blogs/appconsult/23535)
but faced with this error..
error CS0103: The name 'ModelHelper' does not exist in the current context
the codes are as below.
what is this ModelHelper for?
and is there anything that i have to add to use it?
using System;
using System.Linq;
using System.Threading.Tasks;
#if UNITY_WSA && !UNITY_EDITOR
using Windows.Media.Capture;
using Windows.Media.Capture.Frames;
using Windows.Media.MediaProperties;
public class ScanEngine
{
public TimeSpan PredictionFrequency = TimeSpan.FromMilliseconds(400);
private MediaCapture CameraCapture;
private MediaFrameReader CameraFrameReader;
private Int64 FramesCaptured;
IUnityScanScene UnityApp;
public ScanEngine()
{
}
public async Task Inititalize(IUnityScanScene unityApp)
{
UnityApp = unityApp;
await InitializeCameraCapture();
await InitializeCameraFrameReader();
}
private async Task InitializeCameraCapture()
{
CameraCapture = new MediaCapture();
MediaCaptureInitializationSettings settings = new
MediaCaptureInitializationSettings();
settings.StreamingCaptureMode = StreamingCaptureMode.Video;
await CameraCapture.InitializeAsync(settings);
}
private async Task InitializeCameraFrameReader()
{
var frameSourceGroups = await MediaFrameSourceGroup.FindAllAsync();
MediaFrameSourceGroup selectedGroup = null;
MediaFrameSourceInfo colorSourceInfo = null;
foreach (var sourceGroup in frameSourceGroups)
{
foreach (var sourceInfo in sourceGroup.SourceInfos)
{
if (sourceInfo.MediaStreamType == MediaStreamType.VideoPreview
&& sourceInfo.SourceKind == MediaFrameSourceKind.Color)
{
colorSourceInfo = sourceInfo;
break;
}
}
if (colorSourceInfo != null)
{
selectedGroup = sourceGroup;
break;
}
}
var colorFrameSource = CameraCapture.FrameSources[colorSourceInfo.Id];
var preferredFormat = colorFrameSource.SupportedFormats.Where(format =>
{
return format.Subtype == MediaEncodingSubtypes.Argb32;
}).FirstOrDefault();
CameraFrameReader = await CameraCapture.CreateFrameReaderAsync(colorFrameSource);
await CameraFrameReader.StartAsync();
}
public void StartPullCameraFrames()
{
Task.Run(async () =>
{
for (; ; ) // Forever = While the app runs
{
FramesCaptured++;
await Task.Delay(PredictionFrequency);
using (var frameReference = CameraFrameReader.TryAcquireLatestFrame())
using (var videoFrame = frameReference?.VideoMediaFrame?.GetVideoFrame())
{
if (videoFrame == null)
{
continue; //ignoring frame
}
if (videoFrame.Direct3DSurface == null)
{
videoFrame.Dispose();
continue; //ignoring frame
}
try
{
await
ModelHelper.EvaluateVideoFrameAsync(videoFrame).ConfigureAwait(false);
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine(ex.Message);
}
finally
{
}
}
}
});
}
}
#endif