This looks great and works, but in all of these (include?, size, and max) you had to account for that last node separately -- if you change your loop to while current != nil instead of while current.next_node != nil then you wouldn't need that! I told you to model after display which does it the latter way -- because sometimes you need to do something different with the last case and I wanted that to be the pattern I showed -- but now I want to point out how we could have optimized the pattern just slightly. Hopefully that makes sense!