there is a bug if you try to change direction by rolling over left and right at the same time or up and down at the same time. hitting uo/down together and left/right together when changing direction has a weird pause effect.
It's just jargon. I really don't know why the title isn't just "Conversations with a six-year-old on functions" and "f(x) = x - 3." You lose nothing, increase your audience 100fold, and it's more intellectually honest. It is a less hackernews clickbaity title, though.