/// <summary>
/// Writes a unsigned 64-bit integer to the StreamEx.
/// </summary>
/// <param name="b">64-bit unsigned integer.</param>
/// <param name="seq">Byte sequence a.k.a endianness.</param>
public void WriteUInt64(UInt64 b, BitOrder seq = BitOrder.LittleEndian)
{
Write(b.ToBinary(seq), 0, 8);
}