Async Instantiate All At Once

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

import os
import sys
import asyncio


import ccxt.async_support as ccxt  # noqa: E402

exchanges = {}  # a placeholder for your instances


async def main():
   for id in ccxt.exchanges:
       exchange = getattr(ccxt, id)
       exchanges[id] = exchange()
   # now exchanges dictionary contains all exchange instances...
   print(await exchanges['bittrex'].fetch_order_book('ETH/BTC'))
   # close the aiohttp session object
   for id in exchanges:
       await exchanges[id].close()

asyncio.run(main())