def __init__(self, deferred):
        """
        @param deferred: The L{Deferred} to fire when the first resolution
            result arrives.
        """
        self._deferred = deferred
        self._resolved = False

        @param deferred: The L{Deferred} to fire when the first resolution
            result arrives.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/_resolver.py