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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):
 """Sync the write buffer, then close the cache. If a closed :class:`FileCache` object's methods are called, a :exc:`ValueError` will be raised. """

        self.sync()
        self.sync = self.create = self.delete = self._closed
        self._write_to_file = self._read_to_file = self._closed
        self._key_to_filename = self._filename_to_key = self._closed
        self.__getitem__ = self.__setitem__ = self.__delitem__ = self._closed
        self.__iter__ = self.__len__ = self.__contains__ = self._closed