def __call__(self, server_descriptions):
        writable_servers = writable_server_selector(server_descriptions)
        if writable_servers:
            return writable_servers
        else:
            return secondary_with_tags_server_selector(
                self.tag_sets,
                server_descriptions)
Return matching ServerDescriptions from a list.
dataset/ETHPy150Open mongodb/mongo-python-driver/pymongo/read_preferences.py/PrimaryPreferred.__call__