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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 add_cancel_button(self):
 """Add a cancel button at the bottom of the dialog window."""

        button_box = QDialogButtonBox(QDialogButtonBox.Cancel, self)
        button_box.rejected.connect(self.reject)
        self.layout.addWidget(button_box)