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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 async def init( cls, config: Optional[dict] = None, config_file: Optional[str] = None, _create_db: bool = False, db_url: Optional[str] = None, modules: Optional[Dict[str, List[str]]] = None, ) -> None: """ Sets up Tortoise-ORM. You can configure using only one of ``config``, ``config_file`` and ``(db_url, modules)``. Parameters config: Dict containing config: Example ------- .. code-block:: python3 { 'connections': { # Dict format for connection 'default': { 'engine': 'tortoise.backends.asyncpg', 'credentials': { 'host': 'localhost', 'port': '5432', 'user': 'tortoise', 'password': 'qwerty123', 'database': 'test', } }, # Using a DB_URL string 'default': 'postgres://postgres:@qwerty123localhost:5432/events' }, 'apps': { 'models': { 'models': ['__main__'], # If no default_connection specified, defaults to 'default' 'default_connection': 'default', } } } config_file: Path to .json or .yml (if PyYAML installed) file containing config with same format as above. db_url: Use a DB_URL string. See :ref:`db_url` modules: Dictionary of ``key``: [``list_of_modules``] that defined "apps" and modules that should be discovered for models. _create_db: If ``True`` tries to create database for specified connections, could be used for testing purposes. Raises ------ ConfigurationError For any configuration error """

        if cls._inited:
            await cls.close_connections()
            await cls._reset_apps()
        if int(bool(config) + bool(config_file) + bool(db_url)) != 1:
            raise ConfigurationError(
                'You should init either from "config", "config_file" or "db_url"'
            )

        if config_file:
            config = cls._get_config_from_config_file(config_file)

        if db_url:
            if not modules:
                raise ConfigurationError('You must specify "db_url" and "modules" together')
            config = generate_config(db_url, modules)

        try:
            connections_config = config["connections"]  # type: ignore
        except KeyError:
            raise ConfigurationError('Config must define "connections" section')

        try:
            apps_config = config["apps"]  # type: ignore
        except KeyError:
            raise ConfigurationError('Config must define "apps" section')

        logger.info(
            "Tortoise-ORM startup\n    connections: %s\n    apps: %s",
            str(connections_config),
            str(apps_config),
        )

        await cls._init_connections(connections_config, _create_db)
        cls._init_apps(apps_config)

        cls._inited = True