Academic vs practical Memes

The eternal struggle between theory and reality, illustrated with the elegance of a napkin sketch. What we have here is a linked list implementation of a number classifier that would make computer science professors proud and working developers cry. Sure, in theory, you can determine if a number is odd or even by traversing a linked list where each node points to its opposite classification. Start at "isEven" with 0, follow the pointer once for 1 to get "isOdd", twice for 2 to get back to "isEven"... mathematically sound! Meanwhile, in the real world, the rest of us are just using n % 2 == 0 like normal people and going home at 5pm instead of debugging infinite loops when someone inputs 18,446,744,073,709,551,615.