Async Generator Multiple Tickers

# -*- coding: utf-8 -*-

import asyncio
import ccxt.async_support as ccxt


async def poll(tickers):
   i = 0
   kraken = ccxt.kraken()
   while True:
       symbol = tickers[i % len(tickers)]
       yield (symbol, await kraken.fetch_ticker(symbol))
       i += 1
       await asyncio.sleep(kraken.rateLimit / 1000)


async def main():
   async for (symbol, ticker) in poll(['BTC/USD', 'ETH/BTC', 'BTC/EUR']):
       print(symbol, ticker)


asyncio.run(main())