The "one" side API

A One, OneFrom or OneTo end is a OneProperty<T>:

var ev = db.Get<IEvent>(id);

ev.Venue.IsSet();                        // is a node related?
ev.Venue.Count();                        // 0 or 1
var venue = ev.Venue.Get();              // throws when unset
if (ev.Venue.TryGet(out var v)) { … }
ev.Venue.Contains(someVenueId);

A foreach over a one end yields only what the query included (§24). Use Get or TryGet to load it.