def __call__(self, wr=None):
        try:
            del _finalizer_registry[self._key]
        except KeyError:
            sub_debug('finalizer no longer registered')
        else:
            sub_debug('finalizer calling %s with args %s and kwargs %s',
                     self._callback, self._args, self._kwargs)
            res = self._callback(*self._args, **self._kwargs)
            self._weakref = self._callback = self._args = \
                            self._kwargs = self._key = None
            return res
Run the callback unless it has already been called or cancelled
dataset/ETHPy150Open deanhiller/databus/webapp/play1.3.x/python/Lib/multiprocessing/util.py/Finalize.__call__