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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:
 async def add_all(self, recursive=False):
 """ Add all handleable devices that available at start. :param bool recursive: recursively mount and unlock child devices :returns: whether all attempted operations succeeded """

        tasks = [self.auto_add(device, recursive=recursive)
                 for device in self.get_all_handleable_leaves()]
        results = await gather(*tasks)
        success = all(results)
        return success