code: def add_sidebar(self, component: Component) -> None:
          
          if not self.sidebar:
              raise NoSidebarError('Set `sidebar=True` if you want to use the sidebar.')
  
          if not isinstance(component, Component):
              raise ValueError('component must be Component type, found {}'.format(component))
          # self._track_widget(widget)
          self._controllers.append(component)
docs: Add a widget to the sidebar.
  
          Parameters
          ----------
          component : bowtie._Component
              Add this component to the sidebar, it will be appended to the end.