diff --git a/f8/coroutine.cc b/f8/coroutine.cc
index 1c8796d..01679c4 100644
--- a/f8/coroutine.cc
+++ b/f8/coroutine.cc
@@ -97,6 +97,11 @@ namespace f8
         return awaiter->GetResult();
     }
 
+    std::shared_ptr<a8::Results> Coroutine::CoAwait(std::function<(std::shared_ptr<a8::Awaiter>)> cb)
+    {
+
+    }
+
     void Coroutine::Attach()
     {
         list_add_tail(&exec_entry_, &CoMgr::Instance()->exec_list_);
diff --git a/f8/coroutine.h b/f8/coroutine.h
index 97f345b..6ca251f 100644
--- a/f8/coroutine.h
+++ b/f8/coroutine.h
@@ -19,6 +19,7 @@ namespace f8
         void CoResume();
         void CoYield();
         std::shared_ptr<a8::Results> CoAwait(std::shared_ptr<a8::Awaiter> awaiter);
+        std::shared_ptr<a8::Results> CoAwait(std::function<(std::shared_ptr<a8::Awaiter>)> cb);
         std::shared_ptr<a8::Awaiter> Sleep(long long time);
 
     private: