def getlist(self, key):
        try:
            return dict.__getitem__(self, key)
        except KeyError:
            return []
Callback: web socket has closed. (We also call this manually when
dataset/ETHPy150Open kdart/pycopia/aid/pycopia/dictlib.py/MultiValueDict.getlist--crossover with--dataset/ETHPy150Open erkyrath/tworld/lib/tweblib/handlers.py/PlayWebSocketHandler.on_close