callback error: <class 'AttributeError'> 'str' object has no attribute 'isascii'

I'm using the latest release of radian

$ radian --version
radian version: 0.6.5
r executable: /usr/lib/R/bin/R
r version: 4.1.3
python executable: /usr/bin/python3
python version: 3.6.9

When I run any code, radian exits with the following error:

> 1
callback error: <class 'AttributeError'> 'str' object has no attribute 'isascii'

The docs says that isascii was added in Python 3.7. Looks like radian requires Python 3.7+ now?

Is it possible that it does not require a higher Python version than 3.6.9?

randy3k / radian