inIn addition to previous answers:
It is considered more Pythonic to check if not num % fizz*buzz than if num % fizz*buzz == 0
Also you don't need to use elif if there is a returnreturn statement inside if, so I'd rewrite your get_stringget_string function like this:
def get_string(num, fizz, buzz) if not num % fizz*buzz: return "FizzBuzz" if not num % fizz: return "Fizz" if not num % buzz: return "Buzz" return str(n)