Hi why do you use the method .upper()? its use to uppercase string ..
you can read about it here
the lesson aske you to
1 First, def a function called cube that takes an argument called number. Don't forget the parentheses and the colon!
2 Make that function return the cube of that number (i.e. that number multiplied by itself and multiplied by itself once again)
return number ** 3
return number * number * number
3 Define a second function called by_three that takes an argument called number.
4 if that number is divisible by 3, by_three should call cube(number) and return its result. Otherwise, by_three should return False.
if number % 3 == 0 :