public static long AddEventHandler(T instance, string eventMemberName, Delegate handler)
{
instance.AssertNotNull(nameof(instance));
eventMemberName.AssertNotBlank(nameof(eventMemberName));
handler.AssertNotNull(nameof(handler));
var key = DateTime.UtcNow.Ticks;
var eventMember = Events[eventMemberName];
var reference = new HandlerReference(new WeakReference <T>(instance), eventMember, handler);
eventMember.Add(instance !, handler);
EventHandlers.Add(key, reference);
return(key);
}