// ReadCheckSums reads the values back.
func (c *Checksum) AppendTo(b []byte, parts []byte) []byte {
	if c == nil {
		return nil
	}
	var tmp [binary.MaxVarintLen32]byte
	n := binary.PutUvarint(tmp[:], uint64(c.Type))
	crc := c.Raw
	if c.Type.Trailing() {
		// When we serialize we don't care if it was trailing.
		c.Type ^= ChecksumTrailing
	}
	if len(crc) != c.Type.RawByteLen() {
		return b
	}