public virtual void VisitEntity(EntitySymbol entity)
 {
     Visit(entity.Events);
 }
 public EventSymbol(EntitySymbol parent, IEnumerable<Annotation> annotations, bool isAbstract, Identifier name, Maybe<TypeLookup> @base, IEnumerable<AtomSymbol> properties)
     : base(parent, annotations, isAbstract, name, @base, properties)
 {
 }