input: Write a Python function to implement the quicksort algorithm.
  assert quickSort([42, 56, 2, 67, 23, 10, 14, 7]) == [2, 7, 10, 14, 23, 42, 56, 67]
  assert quickSort([3, 6, 8, 10, 1, 2, 1]) == [1, 1, 2, 3, 6, 8, 10]
  assert quickSort([]) == []
  assert quickSort([1]) == [1]
  assert quickSort([9, 7, 5, 3, 1]) == [1, 3, 5, 7, 9]
output: def quickSort(arr):
      if len(arr) <= 1:
          return arr
      pivot = arr[len(arr) // 2]
      left = [x for x in arr if x < pivot]
      middle = [x for x in arr if x == pivot]
      right = [x for x in arr if x > pivot]
      return quickSort(left) + middle + quickSort(right)