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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 accel_prev(self, *args):
 """Callback to go to the previous tab. Called by the accel key. """

        if self.get_notebook().get_current_page() == 0:
            self.get_notebook().set_current_page(self.get_notebook().get_n_pages() - 1)
        else:
            self.get_notebook().prev_page()
        return True