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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 text_filter_changed(self, text):
 """ Called to handle changes to the text filter. :param text: The text for the filter. """

        text = text.strip() if text else None

        if text is not None:
            self.__text_filter = ListModel.TextFilter("text_for_filter", text)
        else:
            self.__text_filter = None

        self.__update_filter()