code: def get_runtime_dir(self, default=True):
          
          dir_ = self._runtime_dir
  
          if not dir_ and default:
              uid = self.main_process.get_owner()[0]
              dir_ = '/run/user/%s/' % uid if uid else '/run/'
  
          return dir_
docs: Directory to store runtime files.
          See ``.replace_placeholders()``
  
          .. note:: This can be used to store PID files, sockets, master FIFO, etc.
  
          :param bool default: Whether to return [system] default if not set.
  
          :rtype: str|unicode