code: def densenet121(num_classes=1000, pretrained='imagenet'):
      r
      model = models.densenet121(pretrained=False)
      if pretrained is not None:
          settings = pretrained_settings['densenet121'][pretrained]
          model = load_pretrained(model, num_classes, settings)
      model = modify_densenets(model)
      return model
docs: r"""Densenet-121 model from
      `"Densely Connected Convolutional Networks" <https://arxiv.org/pdf/1608.06993.pdf>`