def get_events(self, from_=None, to=None):
        """Query a slice of the events.

        Events are always returned in the order the were added.

        Does never throw EventOrderError because it is hard to detect
        from an append-only file.

        Parameters:
        from_   -- if not None, return only events added after the event with
                   id `from_`. If None, return from the start of history.
        to      -- if not None, return only events added before, and
                   including, the event with event id `to`. If None, return up
                   to, and including, the last added event.

        returns -- an iterable of (event id, eventdata) tuples.

        """
        assert from_ is None or isinstance(from_, str)
        assert to is None or isinstance(to, str)
        self._close()
        try:
            return self._unsafe_get_events(from_=from_, to=to)
        finally:
            self._open()