func (tlz4 *TarLz4) Archive(sources []string, destination string) error {
	err := tlz4.CheckExt(destination)
	if err != nil {
		return fmt.Errorf("output %s", err.Error())
	}
	tlz4.wrapWriter()
	return tlz4.Tar.Archive(sources, destination)
}
Archive creates a compressed tar file at destination
containing the files listed in sources. The destination
must end with ".tar.lz4" or ".tlz4". File paths can be
those of regular files or directories; directories will
be recursively added.
package archiver
import (
	"fmt"
	"io"
	"strings"
	"github.com/pierrec/lz4"
)
type TarLz4 struct {
	*Tar
	CompressionLevel int
}
func (*TarLz4) CheckExt(filename string) error {
	if !strings.HasSuffix(filename, ".tar.lz4") &&
		!strings.HasSuffix(filename, ".tlz4") {
		return fmt.Errorf("filename must have a .tar.lz4 or .tlz4 extension")
	}
	return nil
}