Let task foo() be a coroutine. I want to support:

co_await foo()

What would be the best way to do it?

• Implement task::promise_type::await_transform that return an Awaiter.
• Implement Awaiter final_suspend() in task::promise_type, like Lewis Baker code here: https://godbolt.org/z/3qKqWEqYG
• Implement a global operator co_await(task&& t)
• Implement operator co_await() in task

Any thoughts, knowledge, or practice on the mater?