Get the checksum of the RPM Database.

    Returns:
        hexdigest

def _get_checksum():
    """
    Get the checksum of the RPM Database.

    Returns:
        hexdigest
    """
    digest = hashlib.sha256()
    with open(RPM_PATH, "rb") as rpm_db_fh:
        while True:
            buff = rpm_db_fh.read(0x1000)
            if not buff:
                break
            digest.update(buff)
    return digest.hexdigest()