def is_default_extra(extra: bytes) -> bool:
    """Checks if the tx_extra follows the standard format of:
            0x01 <pubkey> 0x02 0x09 0x01 <encrypted_payment_id>
    :param extra: Potential default extra bytes.
    :type extra: bytes
    :return: True if the passed in bytes are in the default tx_extra format
    :rtype: bool
    """

    if len(extra) != 1 + 32 + 1 + 1 + 1 + 8:
        return False
    if (
        extra[0] == 0x01
        and extra[33] == 0x02
        and extra[34] == 0x09
        and extra[35] == 0x01
    ):
        return True
    return False