from time import time
import asyncio

async def call_periodically(interval, func, *args, **kwargs):
    start_time = time()
    while True:
        print('calling', func)
        yield await func(*args, **kwargs)  # <-- I want this to block
        await asyncio.sleep(
            interval - ((time() - start_time) % interval)
        )

async def sample_func():
    print('sleeping...')
    await asyncio.sleep(1)
    print('sleep done')
    return 'message'

async def get_messages(func, *args, **kwargs):
    async for message in call_periodically(3, func, *args, **kwargs):
        print(message)
        #await self.message_handler(message)

loop = asyncio.get_event_loop()
loop.run_until_complete(get_messages(sample_func))