code: func (p *Collector) RetrieveOne(ctx context.Context, obj types.ManagedObjectReference, ps []string, dst interface{}) error {
  	var objs = []types.ManagedObjectReference{obj}
  	return p.Retrieve(ctx, objs, ps, dst)
  }
docs: // RetrieveOne calls Retrieve with a single managed object reference via Collector.Retrieve().