ImportError: cannot import name 'unquote'

I get the following error when trying to run for the first time:

>     from yarl import URL, unquote
> ImportError: cannot import name 'unquote'

Looking at the web, it seems to be an issue with a recent update to the yarl module. Downgrading the yarl version in the requirements.txt file to yarl==0.18.0 seems to work.

See link: https://github.com/aio-libs/aiohttp/issues/2662