def delete(self, prefix, key, cb):
        _log.debug("Deleting key %s" % prefix + key)
        if prefix + key in self.localstore:
            del self.localstore[prefix + key]
        if (prefix + key) in self.localstore_sets:
            del self.localstore_sets[prefix + key]
        if self.started:
            self.set(prefix, key, None, cb)
        else:
            if cb:
                cb(key, True)

    ### Calvin object handling ###
Delete key: prefix+key (value set to None)
dataset/ETHPy150Open EricssonResearch/calvin-base/calvin/runtime/north/storage.py/Storage.delete