3.9 compatibility

Author: dandavison

tests/nexus/test_workflow_caller_cancellation_types.py

@@ -242,10 +242,10 @@ async def _get_event_time(
     wf_handle: WorkflowHandle,
     event_type: EventType.ValueType,
 ) -> datetime:
-    event = await anext(
-        e async for e in wf_handle.fetch_history_events() if e.event_type == event_type
-    )
-    return event.event_time.ToDatetime().replace(tzinfo=timezone.utc)
+    async for event in wf_handle.fetch_history_events():
+        if event.event_type == event_type:
+            return event.event_time.ToDatetime().replace(tzinfo=timezone.utc)
+    assert False, f"Event {event_type} not found in {wf_handle.id}"
 
 
 async def _assert_event_subsequence(