implicit-nullability-via-type-param.bolt

type TemplateType<T> {
  child: T | String;
}

type StringHost {
  keepAlive: String;
  child: TemplateType<String>;
}

// child is optional here, and is statically known.
// but this is gonna be a tough one
type NullHost {
  keepAlive: String;
  child: TemplateType<Null>;
}