def _process_genes(self, limit=None):
        """
        This method processes the KEGG gene IDs.
        The label for the gene is pulled as
        the first symbol in the list of gene symbols;
        the rest are added as synonyms.
        The long-form of the gene name is added as a definition.
        This is hardcoded to just processes human genes.

        Triples created:
        <gene_id> is a SO:gene
        <gene_id> rdfs:label <gene_name>

        :param limit:
        :return:

        """

        LOG.info("Processing genes")
        if self.test_mode:
            graph = self.testgraph
        else:
            graph = self.graph
        model = Model(graph)
        line_counter = 0
        family = Family(graph)
        geno = Genotype(graph)
        raw = '/'.join((self.rawdir, self.files['hsa_genes']['file']))
        with open(raw, 'r', encoding="iso-8859-1") as csvfile:
            filereader = csv.reader(csvfile, delimiter='\t', quotechar='\"')
            for row in filereader:
                line_counter += 1
                (gene_id, gene_name) = row

                gene_id = 'KEGG-'+gene_id.strip()

                # the gene listing has a bunch of labels
                # that are delimited, as:
                # DST, BP240, BPA, BPAG1, CATX-15, CATX15, D6S1101, DMH, DT,
                # EBSB2, HSAN6, MACF2; dystonin; K10382 dystonin
                # it looks like the list is semicolon delimited
                # (symbol, name, gene_class)
                # where the symbol is a comma-delimited list

                # here, we split them up.
                # we will take the first abbreviation and make it the symbol
                # then take the rest as synonyms

                gene_stuff = re.split('r;', gene_name)
                symbollist = re.split(r',', gene_stuff[0])
                first_symbol = symbollist[0].strip()

                if gene_id not in self.label_hash:
                    self.label_hash[gene_id] = first_symbol

                if self.test_mode and gene_id not in self.test_ids['genes']:
                    continue

                # Add the gene as a class.
                geno.addGene(gene_id, first_symbol)

                # add the long name as the description
                if len(gene_stuff) > 1:
                    description = gene_stuff[1].strip()
                    model.addDefinition(gene_id, description)

                # add the rest of the symbols as synonyms
                for i in enumerate(symbollist, start=1):
                    model.addSynonym(gene_id, i[1].strip())

                if len(gene_stuff) > 2:
                    ko_part = gene_stuff[2]
                    ko_match = re.search(r'K\d+', ko_part)
                    if ko_match is not None and len(ko_match.groups()) == 1:
                        ko = 'KEGG-ko:'+ko_match.group(1)
                        family.addMemberOf(gene_id, ko)

                if not self.test_mode and limit is not None and line_counter > limit:
                    break

        LOG.info("Done with genes")
        return
This method processes the KEGG gene IDs.
        The label for the gene is pulled as
        the first symbol in the list of gene symbols;
        the rest are added as synonyms.
        The long-form of the gene name is added as a definition.
        This is hardcoded to just processes human genes.

        Triples created:
        <gene_id> is a SO:gene
        <gene_id> rdfs:label <gene_name>

        :param limit:
        :return: