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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 selected_display_item(self) -> typing.Optional[DisplayItem.DisplayItem]: """Return the selected display item. The selected display is the display ite that has keyboard focus in the data panel or a display panel. """

        # first check for the [focused] data browser
        display_item = self.focused_display_item
        if not display_item:
            selected_display_panel = self.selected_display_panel
            display_item = selected_display_panel.display_item if selected_display_panel else None
        return display_item