code: def _process_pathway_disease(self, limit):
          
          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
docs: 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: