Change backbone and embedder in fastai?

I came across this code on Kaggle to use both efficientnet and a transformer for vision but have never seen something like this in fastai. Are there any examples?:

self.backbone = timm.create_model(backbone, pretrained=pretrained)
self.embedder = timm.create_model(embedder, features_only=True, out_indices=[2], pretrained=pretrained)
self.backbone.patch_embed = HybridEmbed(self.embedder, img_size=CONFIG[‘img_size’], embed_dim=128)