Python asyncio task got bad yield

I am confused about how to play around with the asyncio module in Python 3.4. I have a searching API for a search engine, and want to each search request to be run either parallel, or asynchronously, so that I don't have to wait for one search finish to start another.

Here is my high-level searching API to build some objects with the raw search results. The search engine itself is using some kind of asyncio mechanism, so I won't bother with that.

# No asyncio module used here now
class search(object):
  ...
  self.s = some_search_engine()
  ...
  def searching(self, *args, **kwargs):
    ret = {}
    # do some raw searching according to args and kwargs and build the wrapped results
    ...
    return ret

To try to async the requests, I wrote following test case to test how I can interact my stuff with the asyncio module.

# Here is my testing script
@asyncio.coroutine
def handle(f, *args, **kwargs):
  r = yield from f(*args, **kwargs)
  return r

s = search()
loop = asyncio.get_event_loop()
loop.run_until_complete(handle(s.searching, arg1, arg2, ...))
loop.close()

By running with pytest, it will return a RuntimeError: Task got bad yield : {results from searching...}, when it hits the line r = yield from ....

I also tried another way.

# same handle as above
def handle(..):
  ....
s = search()
loop = asyncio.get_event_loop()
tasks = [
        asyncio.async(handle(s.searching, arg11, arg12, ...)),
        asyncio.async(handle(s.searching, arg21, arg22, ...)),
        ...
        ]
loop.run_until_complete(asyncio.wait(tasks))
loop.close()

By running this test case by pytest, it passes but some weird exception from the search engine will raise. And it says Future/Task exception was never retrieved.

Things I wish to ask:

1. For my 1st try, is that the right way to use yield from, by returning the actual result from a function call?
2. I think I need to add some sleep to my 2nd test case to wait for the task finish, but how should I do that? And how can I get my function calls to return in my 2nd test case?
3. Is that a good way to implement asyncio with an existing module, by creating an async handler to handle requests?
4. If the answer to question 2 is NO, does every client calls to the class search needs to include loop = get_event_loop() this kind of stuffs to async the requests?