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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def grab_next(self, timeout: float=None) -> typing.List[DataAndMetadata.DataAndMetadata]: """Grab the next data to finish from the buffer, blocking until one is available."""

        with self.__buffer_lock:
            self.__buffer = list()
        return self.grab_latest(timeout)