 
             if blockChecksums {
                 let blockChecksum = XxHash32.hash(data: Data(compressedBlock))
-                for i in 0..<4 {
+                for i: UInt32 in 0..<4 {
                     out.append(UInt8(truncatingIfNeeded: (blockChecksum & (0xFF << (i * 8))) >> (i * 8)))
                 }
             }

        // Content checksum.
        if contentChecksum {
            let hash = XxHash32.hash(data: data)
            for i in 0..<4 {
                out.append(UInt8(truncatingIfNeeded: (hash & (0xFF << (i * 8))) >> (i * 8)))
            }
        }

                    fatalError("Patalogical size of compressed block.")
                }
                let blockSize = UInt32(truncatingIfNeeded: compressedBlock.count)
                for i:UInt32 in 0..<4 {
                    out.append(UInt8(truncatingIfNeeded: (blockSize & (0xFF << (i * 8))) >> (i * 8)))
                }
                out.append(contentsOf: compressedBlock)
