docs: def filter(cls, **items):
          '''
          Returns multiple Union objects with search params
          '''
          client = cls._new_api_client(subpath='/search')
          items_dict = dict((k, v) for k, v in list(items.items()))
          json_data = json.dumps(items_dict, sort_keys=True, indent=4)
          return client.make_request(cls, 'post', post_data=json_data)