Asked to code the fizzbuzz test.
Implement fizz_buzz(n), which returns a list containing one result for each integer from 1 through n. Return "FizzBuzz" for numbers divisible by both 3 and 5, "Fizz" for numbers divisible only by 3, "Buzz" for numbers divisible only by 5, and the number itself as a string otherwise. Assume 1 <= n <= 1000.
def fizz_buzz(n):