new_contents: # https://interactivepython.org/runestone/static/pythonds/SortSearch/TheBubbleSort.html
  
  def sort(L):
      n = len(L)
      for i in range(n-1, -1, -1):
          for j in range(i):
              if L[j] > L[j+1]:
                  L[j], L[j+1] = L[j+1], L[j]
  
  
  L = [20, 30, 40, 90, 50, 60, 70, 80, 100, 110]
  sort(L)
  assert L == sorted(L)
  
subject: add bubble sort