python中利用await关键字如何等待Future对象完成详解

import asyncio 
 
 
def mark_done(future, result): 
 print('setting future result to {!r}'.format(result)) 
 future.set_result(result) 
 
 
async def main(loop): 
 all_done = asyncio.Future() 
 
 print('scheduling mark_done') 
 loop.call_soon(mark_done, all_done, 'the result') 
 
 result = await all_done 
 print('returned result: {!r}'.format(result)) 
 
 
event_loop = asyncio.get_event_loop() 
try: 
 event_loop.run_until_complete(main(event_loop)) 
finally: 
 event_loop.close() 

scheduling mark_done
setting future result to 'the result'
returned result: 'the result'