You Try: class Link: >>> a Link(1,Link(2,Link(1))) empty ( >>> b Link(3,Link(2,Link(1))) >>> def __init__(self,first, combined Link(a,Link(b)) rest=empty): How would you retrieve the element 3? self.first first self.rest rest 1.combined.rest.first.rest 2.combined.rest.rest.first 3.combined.rest.first.first 4.combined.first.rest.rest 5.combined.first.rest.firstYou Try: class Link: empty = () def __init__(self, first, rest=empty): self.first = first self.rest = rest >>> a = Link(1, Link(2, Link(1))) >>> b = Link(3, Link(2, Link(1))) >>> combined = Link(a, Link(b)) How would you retrieve the element 3? 1. combined.rest.first.rest 2. combined.rest.rest.first 3. combined.rest.first.first 4. combined.first.rest.rest 5. combined.first.rest.first