code: def _destroy(self):
          
          self.unuse_region()
  
          if self._rlist is not None:
              # Actual client count, which doesn't include the reference kept by the manager, nor ours
              # as we are about to be deleted
              try:
                  if len(self._rlist) == 0:
                      # Free all resources associated with the mapped file
                      self._manager._fdict.pop(self._rlist.path_or_fd())
                  # END remove regions list from manager
              except (TypeError, KeyError):
                  # sometimes, during shutdown, getrefcount is None. Its possible
                  # to re-import it, however, its probably better to just ignore
                  # this python problem (for now).
                  # The next step is to get rid of the error prone getrefcount alltogether.
                  pass
docs: Destruction code to decrement counters