aiohttp: Unclosed client session client_session

It's not an error, just a warning. And you can deal with it by closing the session. Try this:

async def a():
    payload = {}
    url = "https://awebsiteisthere.com"
    curl = AsyncioCurl()
    data = await curl.get(url,payload)
    print(data)
    await curl.session.close()  # this