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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 close(self):
 """ Close the internal epoll file descriptor if it isn't closed :raises OSError: If the underlying ``close(2)`` fails. The error message matches those found in the manual page. """

        with self._close_lock:
            epfd = self._epfd
            if epfd >= 0:
                self._epfd = -1
                close(epfd)