def get_concat_cb(self, key, value, org_cb, org_key, local_list):
        if value:
            value = self.coder.decode(value)
            org_cb(org_key, list(set(value + local_list)))
        else:
            org_cb(org_key, local_list if local_list else None)
get callback
dataset/ETHPy150Open EricssonResearch/calvin-base/calvin/runtime/north/storage.py/Storage.get_concat_cb