public override void RemoveRedundantNodes()
{
if (FirstChild == null && SecondChild != null)
{
ReplaceThisWith(SecondChild);
}
else if (SecondChild == null && FirstChild != null)
{
ReplaceThisWith(FirstChild);
}
else if (FirstChild == null && SecondChild == null)
{
Parent?.RemovePlacement(this);
}
FirstChild?.RemoveRedundantNodes();
SecondChild?.RemoveRedundantNodes();
}