code: func NewEnhancedArchive(a archive.Archive, wrap string) archive.Archive {
  	return EnhancedArchive{
  		a:     a,
  		wrap:  wrap,
  		files: map[string]string{},
  	}
  }
docs: // NewEnhancedArchive enhances a pre-existing archive.Archive instance
  // with this pipe specifics.