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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _update(self):
 """ Update internal state."""

        with self._lock:
            if getmtime(self._filename) > self._last_modified:
                self._last_modified = getmtime(self._filename)
                self._book = ConfigParser(default_section='format')
                self._book.read(self._filename)