def close(self):
if not self._closed:<EOL><INDENT>self.add_event(self._sentinel_event)<EOL>self.flush()<EOL>self._worker.join()<EOL>self._ev_writer.close()<EOL>self._closed = True<EOL><DEDENT>
Flushes the event file to disk and close the file.
        Call this method when you do not need the summary writer anymore.