Simple board

Thanks for noticing the confusing IDs!
Correct me if I'm wrong but all nodes in this board will have coordinates (1,1), but I can see from the method to get nodes by coordinate that this will indeed get the middle node, but not thanks to its internal coordinates (middle nodes internal state) but thanks to its placement in the list. Can we always be sure that the list is structured correctly and thereby the position of the node in the list is gives away its coordinates?