input: Write a function to implement bubble sort.
  assert bubbleSort([64, 34, 25, 12, 22, 11, 90]) == [11, 12, 22, 25, 34, 64, 90]
  assert bubbleSort([5, 1, 4, 2, 8]) == [1, 2, 4, 5, 8]
  assert bubbleSort([3, 0, -2, 6, -1]) == [-2, -1, 0, 3, 6]
output: def bubbleSort(arr):
      n = len(arr)
      for i in range(n):
          for j in range(0, n-i-1):
              if arr[j] > arr[j+1]:
                  arr[j], arr[j+1] = arr[j+1], arr[j]
      return arr