code: def add_renderer(self, klass, *args, **kwargs):
          '''Add a renderer to the current scene.
          
          **Parameter**
          
          klass: renderer class
              The renderer class to be added
          args, kwargs:
              Arguments used by the renderer constructor,
              except for the *widget* argument.
          
          .. seealso:: :py:class:`~chemlab.graphics.renderers.AbstractRenderer`
          .. seealso:: :doc:`/api/chemlab.graphics.renderers`
          
          **Return**
  
          The istantiated renderer. You should keep the return value to
          be able to update the renderer at run-time.
  
          '''
          renderer = klass(self.widget, *args, **kwargs)
          self.widget.renderers.append(renderer)
          return renderef add_renderer(self, klass, *args, **kwargs):
          '''Add a renderer to the current scene.
          
          **Parameter**
          
          klass: renderer class
              The renderer class to be added
          args, kwargs:
              Arguments used by the renderer constructor,
              except for the *widget* argument.
          
          .. seealso:: :py:class:`~chemlab.graphics.renderers.AbstractRenderer`
          .. seealso:: :doc:`/api/chemlab.graphics.renderers`
          
          **Return**
  
          The istantiated renderer. You should keep the return value to
          be able to update the renderer at run-time.
  
          '''
          renderer = klass(self.widget, *args, **kwargs)
          self.widget.renderers.append(renderer)
          return renderer
docs: Add a renderer to the current scene.
          
          **Parameter**
          
          klass: renderer class
              The renderer class to be added
          args, kwargs:
              Arguments used by the renderer constructor,
              except for the *widget* argument.
          
          .. seealso:: :py:class:`~chemlab.graphics.renderers.AbstractRenderer`
          .. seealso:: :doc:`/api/chemlab.graphics.renderers`
          
          **Return**
  
          The istantiated renderer. You should keep the return value to
          be able to update the renderer at run-time.