code: def extract_model_meta(base_meta: dict, extra_meta: dict, model_url: str) -> dict:
      
      meta = {"default": {"default": base_meta["uuid"],
                          "description": base_meta["description"],
                          "code": extra_meta["code"]}}
      del base_meta["model"]
      del base_meta["uuid"]
      meta["model"] = base_meta
      meta["model"].update({k: extra_meta[k] for k in ("code", "datasets", "references", "tags",
                                                       "extra")})
      response = requests.get(model_url, stream=True)
      meta["model"]["size"] = humanize.naturalsize(int(response.headers["content-length"]))
      meta["model"]["url"] = model_url
      meta["model"]["created_at"] = format_datetime(meta["model"]["created_at"])
      return meta
docs: Merge the metadata from the backend and the extra metadata into a dict which is suitable for \
      `index.json`.
  
      :param base_meta: tree["meta"] :class:`dict` containing data from the backend.
      :param extra_meta: dict containing data from the user, similar to `template_meta.json`.
      :param model_url: public URL of the model.
      :return: converted dict.