size       int64
	actualSize int64

	checksum      etag.ETag
	contentSHA256 []byte

	// Content checksum
	contentHash   Checksum
	contentHasher hash.Hash
	disableMD5    bool

	trailer http.Header

	sha256 hash.Hash
}

// Options are optional arguments to NewReaderWithOpts, Options
// simply converts positional arguments to NewReader() into a
// more flexible way to provide optional inputs. This is currently