def get_novel_zwd_accessions(rfam_urs_accs, new_zwd_accs):
    """
    Isolates  all new ZWD URS accessions to imported to Rfam
    with the use of python sets

    rfam_urs_accs: A python dictionary with all Rfam URS accessions
    new_zwd_accs: A python dictionary with all new ZWD URS candidates

    return: A list of novel ZWD URS accessions for import to Rfam
    """

    novel_zwd_accessions = list(set(new_zwd_accs.keys()).difference(set(rfam_urs_accs.keys())))

    return novel_zwd_accessions