/** Return an instance with the provided `Request` replacing the specified header.
 * There are no side effects on the original `Request`.
 *
 * @example
 * ```ts
 * import { withHeader } from "https://deno.land/x/http_utils@$VERSION/message.ts";
 * import { assert } from "https://deno.land/std@$VERSION/testing/asserts.ts";
 *
 * declare const init: Request;
 * declare const header: string;
 * declare const value: string;
 *
 * const request = withHeader(init, header, value);
 *
 * assert(request.headers.get(header), value);
 * assert(init !== request);
 * ```
 *
 * @deprecated Move to [request-utils](https://github.com/httpland/request-utils).
 */
export declare function withHeader(request: Request, fieldName: string, fieldValue: string): Request;
/** Return an instance with the provided `Response` replacing the specified header.
 * There are no side effects on the original `Response`.
 *
 * @example
 * ```ts
 * import { withHeader } from "https://deno.land/x/http_utils@$VERSION/message.ts";
 * import { assert } from "https://deno.land/std@$VERSION/testing/asserts.ts";
 *
 * declare const init: Response;
 * declare const header: string;
 * declare const value: string;
 *
 * const response = withHeader(init, header, value);
 *
 * assert(response.headers.get(header), value);
 * assert(init !== response);
 * ```
 *
 * @deprecated Move to [response-utils](https://github.com/httpland/response-utils).
 */
export declare function withHeader(response: Response, fieldName: string, fieldValue: string): Response;