     private static func processStream(_ pointerData: DataWithPointer) throws -> Data {
         var out: [UInt8] = []
 
-        // STREAM HEADER
-        let streamHeader = try processStreamHeader(pointerData)
+        let streamHeader = try XZStreamHeader(pointerData)
 
         // BLOCKS AND INDEX
         /// Zero value of blockHeaderSize means that we encountered INDEX.

/// Provides unarchive function for XZ archives.
public class XZArchive: Archive {

    enum CheckType: Int {
        case none = 0x00
        case crc32 = 0x01
        case crc64 = 0x04
        case sha256 = 0x0A
    }

    private struct Block {

        let bytes: [UInt8]

        return indexSize + 4
    }

    private static func processFooter(_ streamHeader: XZStreamHeader, _ indexSize: Int,
                                      _ pointerData: DataWithPointer) throws {
        let footerCRC = pointerData.uint32()
        /// Indicates the size of Index field. Should match its real size.
