I'm trying using built\_value in flutter, and found if I declared a Type use built\_value, I can commonly use dot syntax to assign value to it's properties:
my declaration is:

```
abstract class Post implements Built<Post, PostBuilder> {
    Post._();
    int get userId;
    int get id;
    String get title;
    String get body;
    factory Post([updates(PostBuilder b)]) = _$Post;
    static Serializer<Post> get serializer => _$postSerializer;
}

```

and use it like this:

```
Post p = Post();
p.titie = "hello world";

```

got error:

> 
> [dart] No setter named 'title' in class 'Post'.
> 
> 
> 

I'm not familar the `builder` thing, even I found out that the `PostBuilder` have the setter of all properties:
 PostBuilder().title = 'hello world';
but how can I use it?