I'm new of Typescript.
now facing the difficult problem for me.

I want to init Typescript interface field of WebSocketSubjectConfig's 「WebSocketCtor」 field in Rxjs , but i don't know how to do it.

my developing environment is   

npm = 「5.6.0」   

node = 「8.11.1」  

Angular = 「6.0.3」   

rxjs = 「6.2.0」   

below is my code

```
/** setting of websocket */
protected getWebsocketConfig(url:string) : WebSocketSubjectConfig<any>{
    return {
                url: url,
                /*
                I can't init this field. how to init ?
                WebSocketCtor: {
                    WebSocket:new WebSocket(url);
                },
                */
                openObserver: {
                    next: (_e: Event) => {
                        console.log("Websocket is open!!!!");
                        console.dir(_e);
                    }
                },
                closeObserver: {
                    next: (_e: CloseEvent) => {
                        console.log("Websocket is close !!!!")
                    }
                },
           };
}

```

I thought WebSocketSubject's unsubscribe method close websocket connection.
but It's look like don't work.
I think if close the websocket connection , need to implement the 「WebsocketCtor」 and call the Websocket's close method.

the WebSocketSubjectConfig interface is below 

```

export interface WebSocketSubjectConfig {
    ・・・
    openObserver?: NextObserver;
    closeObserver?: NextObserver;
    WebSocketCtor?: {
        new (url: string, protocols?: string | string[]): WebSocket;
    };
}

```

thanks for your cooperation.