docker/tarfile/dest.go
func NewDestination(dest io.Writer, ref reference.NamedTagged) *Destination {
	repoTags := []reference.NamedTagged{}
	if ref != nil {
		repoTags = append(repoTags, ref)
	}
	return &Destination{
		writer:   dest,
		tar:      tar.NewWriter(dest),
		repoTags: repoTags,
		blobs:    make(map[digest.Digest]types.BlobInfo),
	}
}
func NewDestination(dest io.Writer, ref reference.NamedTagged) *Destination {
	repoTags := []reference.NamedTagged{}
	if ref != nil {
		repoTags = append(repoTags, ref)
	}
	return &Destination{
		writer:   dest,
		tar:      tar.NewWriter(dest),
		repoTags: repoTags,
		blobs:    make(map[digest.Digest]types.BlobInfo),
	}
}
// NewDestination returns a tarfile.Destination for the specified io.Writer.