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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 focus_next(self, count=1):
        " Focus the next pane. "
        panes = self.panes
        if panes:
            self.active_pane = panes[(panes.index(self.active_pane) + count) % len(panes)]
        else:
            self.active_pane = None