Impossible
From APIDesign
Explaining something is impossible, is well, impossible. Or at least almost impossible as following few stories show.
You Are the Expert!
Following viral video demonstrates the principle:
You are the expert! Can you do it? And don't tell us it is impossible, as that can only be explained as your own incapability.
Finite-state Machine
This story requires you to understand what a Finite-state machine is and how it differs in capabilities from a pushdown automaton or at least from Turing machine - e.g. classical computer. This kind of knowledge should be approachable to everyone who studied computer science, or who studies lingustics and knows who Chomsky and his hierarchy is.