import { type ProxyRouterHeadersFunction } from "https://deno.land/x/oak@v13.2.5/middleware/proxy.ts";
definition: (ctx: RouterContext<R, P, S>) => HeadersInit | Promise<HeadersInit>
x/oak/middleware/proxy.ts>ProxyRouterHeadersFunction
import { type ProxyRouterHeadersFunction } from "https://deno.land/x/oak@v13.2.5/middleware/proxy.ts";