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

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()