code: func (artifacts *Artifacts) Filter(filter Filter) Artifacts {
  	var result = New()
  	for _, a := range artifacts.items {
  		if filter(a) {
  			result.items = append(result.items, a)
  		}
  	}
  	return result
  }
docs: // Filter filters the artifact list, returning a new instance.
  // There are some pre-defined filters but anything of the Type Filter
  // is accepted.
  // You can compose filters by using the And and Or filters.