u/Either-Edge-7942

https://preview.redd.it/l2qshg6dkqxg1.png?width=1106&format=png&auto=webp&s=898c7501c3a3e600eaac3073cf4c33bdf904a0ad

What am i missing here? I'm trying to get through my final project, hate using Jupyter notebook, but python is giving me issues too. Did i not just define 'yf'???