def source_for_move(self, destination_event):
        """
        The source path corresponding to the given MOVED_TO event.

        If the source path is outside the monitored directories, None
        is returned instead.
        """
        if destination_event.cookie in self._moved_from_events:
            return self._moved_from_events[destination_event.cookie].src_path
        else:
            return None

        The source path corresponding to the given MOVED_TO event.

        If the source path is outside the monitored directories, None
        is returned instead.
        
src/watchdog/observers/inotify_c.py