for child in self.get_children():
    print('Working on', child.first_name, 'to parent', parent.email)
parent = Node.objects.get(id=parent.id)
current_child = Node.objects.get(id=child.id)
current_child.move_to(parent, 'last-child')
current_child.save()
django-mptt: how to successfully move nodes around