return nil
	}
	hasher := c.Type.Hasher()
	_, err := hasher.Write(content)
	if err != nil {
		return err
	}
	sum := hasher.Sum(nil)
	if c.WantParts > 0 && c.WantParts != parts {
		return ChecksumMismatch{
			Want: fmt.Sprintf("%s-%d", c.Encoded, c.WantParts),
			Got:  fmt.Sprintf("%s-%d", base64.StdEncoding.EncodeToString(sum), parts),
		}
	}

	if !bytes.Equal(sum, c.Raw) {
		return ChecksumMismatch{

	finalChecksumType := checksumType | ChecksumMultipart | ChecksumIncludesMultipart
	finalChecksum := NewChecksumFromData(finalChecksumType, checksumCombined)

	// Set WantParts to indicate 3 parts
	finalChecksum.WantParts = 3

	// Test AppendTo serialization
	var serialized []byte
	serialized = finalChecksum.AppendTo(serialized, checksumCombined)

	// Use ChecksumFromBytes to deserialize the final checksum