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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 set_placeholder(self, text):
 """Set the placeholder text that will be displayed when the text is empty and the widget is out of focus :param text: The text for the placeholder :type text: str :raises: None """

        if self._placeholder != text:
            self._placeholder = text
            if not self.hasFocus():
                self.update()