async def fetch(url, session, charset='latin-1'):
    """Fetch a url, using specified ClientSession."""
    try:
        async with session.get(url) as response:
            resp = await response.read()
            print("Fetched: {0:30}".format(url))
            return resp.decode(charset)
    except Exception as e:
        print("Failed to fetch {0:30} with exception : {0:30}".format(url, str(e)))
        return ''