Missing methods in Conversation interface definition

[luaneyed]

I found that Botkit.d.ts does not define some methods of Conversation.
Is the reason the missing methods are not defined is they are private?

I needed successful method and it is not in the definition file, so I wrote code below in my project.

declare module 'botkit' {
  interface Conversation<M extends Message> {
    successful(): boolean;
  }
}

I'd like to add successful to definition file if there is no intentional reason that omitted it!
If then, I wouldn't have to write my own method definition.