How to use the wagtailmedia.forms.get_media_form function in wagtailmedia

def edit(request, media_id):
    Media = get_media_model()
    MediaForm = get_media_form(Media)

    media = get_object_or_404(Media, id=media_id)

    if not permission_policy.user_has_permission_for_instance(request.user, 'change', media):
        return permission_denied(request)

    if request.POST:
        original_file = media.file
        form = MediaForm(request.POST, request.FILES, instance=media, user=request.user)
        if form.is_valid():
            if 'file' in form.changed_data:
                # if providing a new media file, delete the old one.
                # NB Doing this via original_file.delete() clears the file field,
                # which definitely isn't what we want...
                original_file.storage.delete(original_file.name)
            media = form.save()

def add(request, media_type):
    Media = get_media_model()
    MediaForm = get_media_form(Media)

    if request.POST:
        media = Media(uploaded_by_user=request.user, type=media_type)
        form = MediaForm(request.POST, request.FILES, instance=media, user=request.user)
        if form.is_valid():
            form.save()

            # Reindex the media entry to make sure all tags are indexed
            for backend in get_search_backends():
                backend.add(media)

            messages.success(request, _("Media file '{0}' added.").format(media.title), buttons=[
                messages.button(reverse('wagtailmedia:edit', args=(media.id,)), _('Edit'))
            ])
            return redirect('wagtailmedia:index')
        else: