Hello, can you fix all of the code? it just keeps giving me errors for no reason, i've been trying to fix it for like 9 hours now, and i can't find the solution, all of the code says "not define, replace bla bla"

 

code link: https://colab.research.google.com/drive/1p3GZAkFJnWu3MRbt1Mwn-EYkdQn-KAy-?usp=sharing

 

My problem is that whenever i run the code the df heads will start giving errors, you can try it out too, i don't know why, it keeps giving "not defined" bla bla for most of the code.