code: def remove_fetcher(self, fetcher):
          
          self._lock.acquire()
          try:
              for t, f in list(self._active_fetchers):
                  if f is fetcher:
                      self._active_fetchers.remove((t, f))
                      f._deactivated()
                      return
          finally:
              self._lock.release()
docs: Remove a running fetcher from the list of active fetchers.
  
          :Parameters:
              - `fetcher`: fetcher instance.
          :Types:
              - `fetcher`: `CacheFetcher`