code: def local_check (self):
          
          log.debug(LOG_CHECK, "Checking %s", unicode(self))
          # strict extern URLs should not be checked
          assert not self.extern[1], 'checking strict extern URL'
          # check connection
          log.debug(LOG_CHECK, "checking connection")
          try:
              self.check_connection()
              self.set_content_type()
              self.add_size_info()
              self.aggregate.plugin_manager.run_connection_plugins(self)
          except tuple(ExcList) as exc:
              value = self.handle_exception()
              # make nicer error msg for unknown hosts
              if isinstance(exc, socket.error) and exc.args[0] == -2:
                  value = _('Hostname not found')
              elif isinstance(exc, UnicodeError):
                  # idna.encode(host) failed
                  value = _('Bad hostname %(host)r: %(msg)s') % {'host': self.host, 'msg': str(value)}
              self.set_result(unicode_safe(value), valid=False)
docs: Local check function can be overridden in subclasses.