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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _process_pathway_disease(self, limit):
 """ We make a link between the pathway identifiers, and any diseases associated with them. Since we model diseases as processes, we make a triple saying that the pathway may be causally upstream of or within the disease process. :param limit: :return: """

        LOG.info("Processing KEGG pathways to disease ids")
        if self.test_mode:
            graph = self.testgraph
        else:
            graph = self.graph
        line_counter = 0

        raw = '/'.join((self.rawdir, self.files['pathway_disease']['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
                (disease_id, kegg_pathway_num) = row

                if self.test_mode and kegg_pathway_num not in self.test_ids['pathway']:
                    continue

                disease_id = 'KEGG-' + disease_id
                # will look like KEGG-path:map04130 or KEGG-path:hsa04130
                pathway_id = 'KEGG-' + kegg_pathway_num

                graph.addTriple(
                    pathway_id,
                    self.globaltt['causally upstream of or within'],
                    disease_id)

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

        return