code: func MakeIRI(subject, predicate, object, label string) (q Quad) {
  	if subject != "" {
  		q.Subject = IRI(subject)
  	}
  	if predicate != "" {
  		q.Predicate = IRI(predicate)
  	}
  	if object != "" {
  		q.Object = IRI(object)
  	}
  	if label != "" {
  		q.Label = IRI(label)
  	}
  	return
  }
docs: // MakeIRI creates a quad with provided IRI values.