How to use the ubiquerg.system.is_writable function in ubiquerg

def refgenie_initg(rgc, genome, content_checksums):
    """
    Initializing a genome means adding `collection_checksum` attributes in the
    genome config file. This should perhaps be a function in refgenconf, but not
    a CLI-hook. Also adds `content_checksums` tsv file (should be a recipe cmd?).

    This function updates the provided RefGenConf object with the
    genome(collection)-level checksum and saves the individual checksums to a
    TSV file in the fasta asset directory.

    :param refgenconf.RefGenConf rgc: genome configuration object
    :param str genome: name of the genome
    :param dict content_checksums: checksums of individual content_checksums, e.g. chromosomes
    """
    genome_dir = os.path.join(rgc[CFG_FOLDER_KEY], genome)
    if is_writable(genome_dir):
        output_file = os.path.join(genome_dir, "{}_sequence_digests.tsv".format(genome))
        with open(output_file, "w") as contents_file:
            wr = csv.writer(contents_file, delimiter="\t")
            for key, val in content_checksums.items():
                wr.writerow([key, val])
        _LOGGER.debug("sequence digests saved to: {}".format(output_file))
    else:
        _LOGGER.warning("Could not save the genome sequence digests. '{}' is not writable".format(genome_dir))