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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 on_scroll(self, event):
        ''' mouse wheel is used for setting slider value'''
        if event.button == 'up':
            self.next_slice()
        if event.button == 'down':
            self.prev_slice()
        self.actual_slice_slider.set_val(self.actual_slice)