Setup for differnet types of compression for Writer

Added some TODOs

internal/compression/lz4.go

@@ -35,3 +35,21 @@ func (l *Lz4) Decompress(r io.Reader) ([]byte, error) {
 	_, err := io.Copy(&buf, rdr)
 	return buf.Bytes(), err
 }
+
+//Compress implements compression.Compress
+func (l *Lz4) Compress(data []byte) ([]byte, error) {
+	var buf bytes.Buffer
+	w := lz4.NewWriter(&buf)
+	if l.HC {
+		err := w.Apply(lz4.CompressionLevelOption(lz4.Level9))
+		if err != nil {
+			return nil, err
+		}
+	}
+	_, err := w.Write(data)
+	if err != nil {
+		return nil, err
+	}
+	w.Close()
+	return buf.Bytes(), nil
+}