code: def add_subvisual(self, visual):
          
          visual.transforms = self.transforms
          visual._prepare_transforms(visual)
          self._subvisuals.append(visual)
          visual.events.update.connect(self._subv_update)
          self.update()
docs: Add a subvisual
  
          Parameters
          ----------
          visual : instance of Visual
              The visual to add.