Draw layer across all panels

        geoms should not override this method.

        Parameters
        ----------
        data : DataFrame
            DataFrame specific for this layer
        layout : Lanel
            Layout object created when the plot is getting
            built
        coord : coord
            Type of coordinate axes
        params : dict
            Combined *geom* and *stat* parameters. Also
            includes the stacking order of the layer in
            the plot (*zorder*)

def draw_layer(self, data, layout, coord, **params):
        """
        Draw layer across all panels

        geoms should not override this method.

        Parameters
        ----------
        data : DataFrame
            DataFrame specific for this layer
        layout : Lanel
            Layout object created when the plot is getting
            built
        coord : coord
            Type of coordinate axes
        params : dict
            Combined *geom* and *stat* parameters. Also
            includes the stacking order of the layer in
            the plot (*zorder*)
        """
        for pid, pdata in data.groupby('PANEL'):
            if len(pdata) == 0:
                continue
            ploc = pid - 1
            panel_params = layout.panel_params[ploc]
            ax = layout.axs[ploc]
            self.draw_panel(pdata, panel_params, coord, ax, **params)