public void Unify_lis_ref()
{
ListTerm list = new ListTerm();
list.Next = new ConstantTerm("ali");
list.Next.Next = new ConstantTerm("samir");
AbstractTerm term = new AbstractTerm();
Assert.IsTrue(list.Unify(term));
Assert.AreSame(list.Head, term.Head);
Assert.AreSame(list.Tail, term.Tail);
}