This is where all the predicates are kept.

Predicates are sort of like Advancements, except that Advancements are more like Achivements. Predicates are only for detecting things.

For example, the "empty_hand" predicate only checks if a player has an empty hand, and sets itself as "true" if they do. If the predicate is "true", a different function can recall that predicate and do something if it's true.