it means the file doesnt exist. You cant just provide a filename. Wherever your code is being saved is the current working directory. if you want to reference a file, you should provide the full path from root or C drive
Is the file called '3.9.1'? If it is actually named '3.9.1.py' you should refer to it as such.
Also one should not put dots in filenames unless it is for defining file extensions or such errors appear.
Just good programming practice ;)
with this command, you should be able to see name of your python file in a list:
print([i for i in os.listdir() if ".py" in i])
and then you can get full path of your python file with this command: