diff --git a/src/main.rs b/src/main.rs
index a5c2e61..d5d51be 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -18,3 +18,12 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     Ok(())
 }
+
+async fn auth_header(mut req: Request<()>) -> Result<Request<()>, InvalidMetadataValue> {
+
+    let token: MetadataValue<_> = "Bearer my-secret-token".parse()?;
+
+
+	req.metadata_mut().insert("x-goog-api-key", token).expect("WHAT");
+	Ok(req)
+}