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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_scroller_widget(self, ref, left=1, top=1, right=20, bottom=1, direction="h", speed=1, text="Message"):
 """ Add Scroller Widget """

        
        if ref not in self.widgets:   
            widget = ScrollerWidget(screen=self, ref=ref, left=left, top=top, right=right, bottom=bottom, direction=direction, speed=speed, text=text)
            self.widgets[ref] = widget
            return self.widgets[ref]