def int_to_bytes(int_value: int, length: int) -> bytes:
    """
    convert an integer to a sequence of bytes using big endian byte ordering
    :param int_value: integer value to convert
    :param length: (optional) byte length
    :return: byte sequence
    """
    if length == 1:
        fmt = "!B"
    elif length == 2:
        fmt = "!H"
    return pack(fmt, int_value)