old_contents: from nolang.error import AppError
  from nolang.objects.root import W_Root
  
  
  class W_ListObject(W_Root):
      def __init__(self, w_items):
          self._w_items = w_items
  
      def str(self, space):
          return '[' + ', '.join([space.str(i) for i in self._w_items]) + ']'
  
      def len(self, space):
          return len(self._w_items)
  
      def unwrap_index(self, space, w_index):
          try:
              i = space.int_w(w_index)
          except AppError as ae:
              if space.type(ae.w_exception) == space.w_typeerror:
                  raise space.apperr(space.w_typeerror, 'list index must be int')
              raise
          if i < 0 or i >= len(self._w_items):
              raise space.apperr(space.w_indexerror, 'list index out of range')
          return i
  
      def getitem(self, space, w_index):
          return self._w_items[self.unwrap_index(space, w_index)]
  
      def setitem(self, space, w_index, w_value):
          self._w_items[self.unwrap_index(space, w_index)] = w_value
  
new_contents: from nolang.error import AppError
  from nolang.objects.root import W_Root
  
  
  class W_ListObject(W_Root):
      def __init__(self, w_items):
          self._w_items = w_items
  
      def str(self, space):
          return '[' + ', '.join([space.str(i) for i in self._w_items]) + ']'
  
      def len(self, space):
          return len(self._w_items)
  
      def unwrap_index(self, space, w_index):
          try:
              i = space.int_w(w_index)
          except AppError as ae:
              if space.type(ae.w_exception) is space.w_typeerror:
                  raise space.apperr(space.w_typeerror, 'list index must be int')
              raise
          if i < 0 or i >= len(self._w_items):
              raise space.apperr(space.w_indexerror, 'list index out of range')
          return i
  
      def getitem(self, space, w_index):
          return self._w_items[self.unwrap_index(space, w_index)]
  
      def setitem(self, space, w_index, w_value):
          self._w_items[self.unwrap_index(space, w_index)] = w_value
  
subject: Use is instead of == for types.