code: def trigger(self, identifier, force=True):
          
          self.debug(identifier)
          url = "{base}/{identifier}".format(
              base=self.local_base_url,
              identifier=identifier
          )
          param = {}
          if force:
              param['force'] = force
          encode = urllib.urlencode(param)
          if encode:
              url += "?"
              url += encode
          return self.core.update(url, {})
docs: Trigger an upgrade task.