func part(blob *test.Blob, offset, size uint64) *BytesPart { return &BytesPart{BlobRef: blob.BlobRef(), Size: size, Offset: offset} }
func all(blob *test.Blob) *BytesPart { return part(blob, 0, uint64(blob.Size())) }
func all(blob *test.Blob) *ContentPart { return part(blob, 0, uint64(blob.Size())) }