def _get_layout_names(self):
        """
        Returns a sequence of tuples of layout name and lowercased class name
        strings for each available layout.
        """

        layouts = itertools.chain(
            self.qtile.config.layouts,
            (layout for group in self.qtile.config.groups for layout in group.layouts),
        )

        return set((layout.name, layout.__class__.__name__.lower()) for layout in layouts)

        Returns a sequence of tuples of layout name and lowercased class name
        strings for each available layout.
        
libqtile/widget/currentlayout.py