new_contents: def quicksort(list, left, right):
  	if left < right:
  		pivot_index = partition(list, left, right)
  		quicksort(list, left, pivot_index-1)
  		quicksort(list, pivot_index+1, right)
  
  def partition(list, left, right):
  	low = left
  	high = right + 1
  	pivot = list[left]
  	while True:
  		# do increment low index while list[low] is smaller than pivot
  		while True:
  			low += 1
  			if list[low] >= pivot:
  				break
  
  		# do decrement high index while list[high] is bigger than pivot
  		while True:
  			high -= 1
  			if list[high] <= pivot:
  				break
  
  		# if low index is smaller than high index, swap their element
  		if low < high:
  			list[low], list[high] = list[high], list[low]
  		else:
  			break
  
  	# swap pivot value to high element
  	list[left], list[high] = list[high], list[left]
  
  	return high
  
  if __name__ == "__main__":
  	list = [67, 90, 57, 25, 84, 32, 73, 54]
  	print("=== Before ===")
  	print(list)
  
  	quicksort(list, 0, len(list)-1)
  
  	print("=== After ===")
  	print(list)
  
subject: Add a quicksort algorithm