def __init__(self, th=None):
        """
        Args:
            th (threading.Thread or None):
        """
        super(ShareSessionThread, self).__init__()
        if th is not None:
            assert isinstance(th, threading.Thread), th
            self._th = th
            self.name = th.name
            self.daemon = th.daemon

        Args:
            th (threading.Thread or None):
        
tensorpack/utils/concurrency.py