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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 terminate(self):
 """ Terminate Qutepart instance. This method MUST be called before application stop to avoid crashes and some other interesting effects Call it on close to free memory and stop background highlighting """

        self.text = ''
        self._completer.terminate()

        if self._highlighter is not None:
            self._highlighter.terminate()

        if self._vim is not None:
            self._vim.terminate()