usestd::fmt::Debug;usestd::hash::Hash;/// An entity is a thing that exists in an ontology — an object in the category.
////// Entities must be finite and enumerable. Every entity can list all possible
/// values of its type, enabling exhaustive validation of ontology properties.
pubtraitEntity: Sized + Clone + Eq + Hash + Debug {/// All possible entities of this type.
fnvariants()->Vec<Self>;}