docs: def push(self):
          """Push topics to Transifex."""
  
          tx = Tx(self.tx_project_slug)
  
          # asssemble the template catalog
          template = babel.messages.catalog.Catalog()
          for topic in self.desk.topics():
              if topic.show_in_portal:
                  template.add(topic.name)
  
          # serialize the catalog as a PO file
          template_po = StringIO()
          babel.messages.pofile.write_po(template_po, template)
  
          # upload/update the catalog resource
          tx.create_or_update_resource(
              self.TOPIC_STRINGS_SLUG,
              DEFAULT_SOURCE_LANGUAGE,
              "Help Center Topics",
              template_po.getvalue(),
              i18n_type='PO',
              project_slug=self.tx_project_slug,
          )