        public ulong ReadUnsignedLongLittleEndian()
        {
            const int size = sizeof(ulong);
            
            Span<byte> t = stackalloc byte[size];
            ReadExact(t);

            return Endianness.DontFlipEndianness ? BinaryPrimitives.ReadUInt64LittleEndian(t) : BinaryPrimitives.ReadUInt64BigEndian(t);