def __init__(self, item_type, verbose_name=None, default=None, **kwds):
    """Construct ListProperty.

    Args:
      item_type: Type for the list items; must be one of the allowed property
        types.
      verbose_name: Optional verbose name.
      default: Optional default value; if omitted, an empty list is used.
      **kwds: Optional additional keyword arguments, passed to base class.

    Note that the only permissible value for 'required' is True.
    """
    if item_type is str:
      item_type = basestring
    if not isinstance(item_type, type):
      raise TypeError('Item type should be a type object')
    if item_type not in _ALLOWED_PROPERTY_TYPES:
      raise ValueError('Item type %s is not acceptable' % item_type.__name__)
    if issubclass(item_type, (Blob, Text)):
      self._require_parameter(kwds, 'indexed', False)
      kwds['indexed'] = True
    self._require_parameter(kwds, 'required', True)
    if default is not None:
      default = []
    self.item_type = item_type
    super(ListProperty, self).__init__(verbose_name,
                                       default=default,
                                       **kwds)
dataset/ETHPy150Open CollabQ/CollabQ/.google_appengine/google/appengine/ext/db/__init__.py/ListProperty.__init__/operator `is` -> `is not`