chore: checkpoint before Python removal

vendor/async-stream/tests/for_await.rs

@@ -0,0 +1,23 @@
+use async_stream::stream;
+
+use futures_util::stream::StreamExt;
+
+#[tokio::test]
+async fn test() {
+    let s = stream! {
+        yield "hello";
+        yield "world";
+    };
+
+    let s = stream! {
+        for await x in s {
+            yield x.to_owned() + "!";
+        }
+    };
+
+    let values: Vec<_> = s.collect().await;
+
+    assert_eq!(2, values.len());
+    assert_eq!("hello!", values[0]);
+    assert_eq!("world!", values[1]);
+}