code: func (q InternalQuad) Get(d quad.Direction) graph.Value {
  	switch d {
  	case quad.Subject:
  		return q.Subject
  	case quad.Predicate:
  		return q.Predicate
  	case quad.Object:
  		return q.Object
  	case quad.Label:
  		return q.Label
  	default:
  		return nil
  	}
  }
docs: // Get returns a specified direction of the quad.