def _initialize_properties(model_class, name, bases, dct):
  model_class._properties = {}
  property_source = {}

  def get_attr_source(name, cls):
    for src_cls  in cls.mro():
      if name in src_cls.__dict__:
        return src_cls

  defined = set()
  for base in bases:
    if hasattr(base, '_properties'):
      property_keys = set(base._properties.keys())
      duplicate_property_keys = defined & property_keys
      for dupe_prop_name in duplicate_property_keys:
        old_source = property_source[dupe_prop_name] = get_attr_source(
            dupe_prop_name, property_source[dupe_prop_name])
        new_source = get_attr_source(dupe_prop_name, base)
        if old_source != new_source:
          raise DuplicatePropertyError(
              'Duplicate property, %s, is inherited from both %s and %s.' %
              (dupe_prop_name, old_source.__name__, new_source.__name__))
      property_keys -= duplicate_property_keys
      if property_keys:
        defined |= property_keys
        property_source.update(dict.fromkeys(property_keys, base))
        model_class._properties.update(base._properties)

  for attr_name in dct.keys():
    attr = dct[attr_name]
    if isinstance(attr, Property):
      check_reserved_word(attr_name)
      if attr_name in defined:
        raise DuplicatePropertyError('Duplicate property: %s' % attr_name)
      defined.add(attr_name)
      model_class._properties[attr_name] = attr
      attr.__property_config__(model_class, attr_name)

  model_class._unindexed_properties = frozenset(
    name for name, prop in model_class._properties.items() if not prop.indexed)
Receiver function to setup all users config variables. They are grouped
dataset/ETHPy150Open CollabQ/CollabQ/.google_appengine/google/appengine/ext/db/__init__.py/_initialize_properties--crossover with--dataset/ETHPy150Open OpenSlides/OpenSlides/openslides/users/signals.py/setup_users_config