def retrieve(
        self,
        model_id: str,
        *,
        betas: List[AnthropicBetaParam] | NotGiven = NOT_GIVEN,
        # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
        # The extra values given here take precedence over values defined on the client or passed to this method.
        extra_headers: Headers | None = None,
        extra_query: Query | None = None,
        extra_body: Body | None = None,
        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
    ) -> BetaModelInfo:
        """
        Get a specific model.

        The Models API response can be used to determine information about a specific
        model or resolve a model alias to a model ID.

        Args:
          model_id: Model identifier or alias.

          betas: Optional header to specify the beta version(s) you want to use.

          extra_headers: Send extra headers

          extra_query: Add additional query parameters to the request

          extra_body: Add additional JSON properties to the request

          timeout: Override the client-level default timeout for this request, in seconds
        """
        if not model_id:
            raise ValueError(f"Expected a non-empty value for `model_id` but received {model_id!r}")
        extra_headers = {
            **strip_not_given({"anthropic-beta": ",".join(str(e) for e in betas) if is_given(betas) else NOT_GIVEN}),
            **(extra_headers or {}),
        }
        return self._get(
            f"/v1/models/{model_id}?beta=true",
            options=make_request_options(
                extra_headers=extra_headers, extra_query=extra_query, extra_body=extra_body, timeout=timeout
            ),
            cast_to=BetaModelInfo,
        )

        Get a specific model.

        The Models API response can be used to determine information about a specific
        model or resolve a model alias to a model ID.

        Args:
          model_id: Model identifier or alias.

          betas: Optional header to specify the beta version(s) you want to use.

          extra_headers: Send extra headers

          extra_query: Add additional query parameters to the request

          extra_body: Add additional JSON properties to the request

          timeout: Override the client-level default timeout for this request, in seconds
        
src/anthropic/resources/beta/models.py