I don't understand how to use `RETURNING`, e.g. how to get the actual value "in my hands" for next steps. Assume, I have two tables:

```
create table "actors" (
  id_act serial not null primary key,
  first_name text not null,
  last_name text not null
);
create table movies (
  id_mov serial not null primary key,
  act_id integer not null
);

```

Now I add an actor:

```
INSERT INTO actors (first_name, last_name) VALUES ('Tom', 'Hanks');

```

and immediately after that, I'd like to use that new actor's-ID to insert a movie:

```
INSERT INTO movies(###);

```

How can I use `RETURNING` to use it instead of my placeholder ###?