Methods that return the highest score from the list

[erfanakbari1]

Hello guys !
I just got an exercise to do and I wrote some code for this task but unfortunately I'm facing some errors !
The task is :

# to write methods that return the highest score from the list, the last added score and the three highest 
# scores.

I solved the first ones ( return highest score and the last added score successfully . ) but I got stuck in last one which is to return the three highest scores
and this is my code and functions for doing it

def Three_highest_scores(a, b, c):
    for j in gamePlayersList:
        a = max(gamePlayersList)
        print(j)
        return a

        for f in gamePlayersList:
            if f < a:
                b = max(f)
                print(f)
                return b

                for x in gamePlayersList:
                    if a > x < f:
                        c = max(x)
                        print(x)
                        return c


Three_highest_scores(max(gamePlayersList), max(f), max(x))
print(Three_highest_scores())

And this is the error :

 Three_highest_scores(max(gamePlayersList), max(f), max(x))
NameError: name 'f' is not defined 

So , I'm very thankful if you can help me fix these issues .
Thanks