void Initialization(T element)
{
first = new NodeDoble <T>();
last = new NodeDoble <T>();
first.SetValue(element);
last = first;
first.children = last;
}
public void SetChildren(T newChildren)
{
var newNode = new NodeDoble <T>();
newNode.SetValue(newChildren);
children = newNode;
children.father = this;
}