new_contents: def divide(x, y):
      if x == 0: return (0, 0)
      quotient, rest = divide(x/2, y)
      quotient *= 2
      rest *= 2
      if x % 2 == 1:
          rest += 1
      if rest >= y:
          rest -= y
          quotient += 1
      print "quotient ", quotient,"rest ", rest
      return (quotient, rest)
  
  #assert divide(4, 2) == (2, 0)
  assert divide(17, 3) == (5, 2)
  # assert divide(10, 15) == (0, 10)
  # assert divide(14, 5) == (2, 4)
  
subject: add divide with recursivity