> It won't work if each method returns a new instance, such as methods of immutable collections. TS' this type does not allow that either. You have to return `

> It won't work if each method returns a new instance, such as methods of immutable collections. TS' this type does not allow that either. You have to return `this`, and nothing else. This can be explained by inheritance. If you extend a class with a method returning a `this` type, but not returning `this`, somehow you should be forced to override that method. But you probably don't want that. Also, the `this` type introduced by TS is basically equivalent to Scala's `this.type`.