# File lib/more/facets/linkedlist.rb, line 128
        def push(v)
                if @lookup.has_key?(v)
                        n = @lookup[v]
                        node_delete(n)
                        node_join(@tail.prev_node,n)
                        node_join(n,@tail)
                else
                        n = Node.new(v,v,@tail.prev_node,@tail)
                        node_join(@tail.prev_node,n)
                        node_join(n,@tail)
                        @lookup[v] = n
                end
                v
        end