new_contents: def quick_sort(array):
  
      quick_sort_help(array, 0, len(array) - 1)
  
      return array
  
  def quick_sort_help(array, first, last):
  
      if first < last:
          splitPoint = partition(array, first, last)
  
          quick_sort_help(array, first, splitPoint-1)
          quick_sort_help(array, splitPoint+1, last)
  
      return array
  
  def partition(array, first, last):
  
      pivotValue = array[first]
  
      leftMark = first+1
      rightMark = last
  
      done = False
  
      while not done:
  
          while leftMark <= rightMark and array[leftMark] <= pivotValue:
              leftMark += 1
  
          while rightMark >= leftMark and array[rightMark] >= pivotValue:
              rightMark -= 1
  
          if rightMark < leftMark:
              done = True
  
          else:
              array[leftMark], array[rightMark] = array[rightMark], array[leftMark]
  
      array[first], array[rightMark] = array[rightMark], array[first]
  
      return rightMark
  
  array = [23, 1, 90, 11, 9, 999, 12]
  print(quick_sort(array))
subject: add Quick Sort