code: def _process_pathways(self, limit=None):
          
  
          LOG.info("Processing pathways")
          if self.test_mode:
              graph = self.testgraph
          else:
              graph = self.graph
          model = Model(graph)
          line_counter = 0
          path = Pathway(graph)
          raw = '/'.join((self.rawdir, self.files['pathway']['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
                  (pathway_id, pathway_name) = row
  
                  if self.test_mode and pathway_id not in self.test_ids['pathway']:
                      continue
  
                  pathway_id = 'KEGG-'+pathway_id.strip()
                  path.addPathway(pathway_id, pathway_name)
  
                  # we know that the pathway images from kegg map 1:1 here.
                  # so add those
                  image_filename = re.sub(r'KEGG-path:', '', pathway_id) + '.png'
                  image_url = 'http://www.genome.jp/kegg/pathway/map/'+image_filename
                  model.addDepiction(pathway_id, image_url)
  
                  if not self.test_mode and limit is not None and line_counter > limit:
                      break
  
          LOG.info("Done with pathways")
          return
docs: This method adds the KEGG pathway IDs.
          These are the canonical pathways as defined in KEGG.
          We also encode the graphical depiction
          which maps 1:1 with the identifier.
  
          Triples created:
          <pathway_id> is a GO:signal_transduction
          <pathway_id> rdfs:label <pathway_name>
          <gene_id> RO:involved_in <pathway_id>
          :param limit:
          :return: