Even if it may not matter in this case specifically, this is a terrible example. "sudo chmod 777" in public code is basically "I don't know what I'm doing, but go on, do the same thing yourself" :(
You don't need sudo, because it's your file. You need just "chmod 755", not "777". And you don't need chmod in the first place - just run "python script_demo.py".
You don't need sudo, because it's your file. You need just "chmod 755", not "777". And you don't need chmod in the first place - just run "python script_demo.py".