You Try: a Link(1,link(2,link(1))) 2 b Link(3,link(2,link(1))) 3 combined.rest is an arrow to the next link combined.rest.first is an arrow to b combined Link(a,: Link(b.)) combined.rest:first firstYou Try: b = Link(3, link(2, link(1))) combined.rest is an arrow to the next link combined.rest.first is an arrow to b 3 2 1 combined = Link(a, Link(b)) 1 2 1 a = Link(1, link(2, link(1))) combined.rest.first.first