code: func NewCompressedTarReader(rs io.ReadSeeker) (*TarReadCloser, error) {
  	cr, err := NewCompressedReader(rs)
  	if err != nil {
  		return nil, err
  	}
  	return &TarReadCloser{tar.NewReader(cr), cr}, nil
  }
docs: // NewCompressedTarReader creates a new TarReadCloser reading from the
  // given ACI image.
  // It is the caller's responsibility to call Close on the TarReadCloser
  // when done.