'Yields tuples of (full_path, suffix_only) for suffixes stored
on the given device and partition.
:param device: name of target device
:param partition: partition name
:param policy: the StoragePolicy instance'

def yield_suffixes(self, device, partition, policy):

    dev_path = self.get_dev_path(device)
    if (not dev_path):
        raise DiskFileDeviceUnavailable()
    partition_path = get_part_path(dev_path, policy, partition)
    for suffix in self._listdir(partition_path):
        if (len(suffix) != 3):
            continue
        try:
            int(suffix, 16)
        except ValueError:
            continue
        (yield (os.path.join(partition_path, suffix), suffix))
