feature: serverus modularly serves up a directory as an HTTP server

tests/handlers/foo.ts

@@ -0,0 +1,22 @@
+import * as path from '@std/path';
+/**
+ * Any request that is for something with the extension 'foo' should return 'foo'
+ *
+ * @param request The incoming HTTP request
+ * @returns Either a response (a foo) or undefined if unhandled.
+ */
+export default function handle_static_files(request: Request): Response | undefined {
+	const url: URL = new URL(request.url);
+	const extension: string = path.extname(url.pathname)?.slice(1)?.toLowerCase() ?? '';
+
+	if (extension !== 'foo') {
+		return;
+	}
+
+	return new Response('foo', {
+		status: 200,
+		headers: {
+			'Content-Type': 'text/plain'
+		}
+	});
+}