def _set_current_context(self, device_id):
        """Sets the number of the currently handled device.

        Parameters
        ----------
        device_id : int
            The number of current device.
        """
        if device_id not in self._all_index_update_counts:
            self._all_index_update_counts[device_id] = {}
        self._index_update_count = self._all_index_update_counts[device_id]