code: def setup(app):
      ''' Required Sphinx extension setup function. '''
      app.add_node(bokeh_palette_group, html=(html_visit_bokeh_palette_group, None))
      app.add_directive('bokeh-palette-group', BokehPaletteGroupDirectivef setup(app):
      ''' Required Sphinx extension setup function. '''
      app.add_node(bokeh_palette_group, html=(html_visit_bokeh_palette_group, None))
      app.add_directive('bokeh-palette-group', BokehPaletteGroupDirective)
docs: Required Sphinx extension setup function.