Interface Subscription (4.4.0)

on(event: 'message', listener: (message: Message) => void): this;

on(event: 'error', listener: (error: StatusError) => void): this;

on(event: 'close', listener: () => void): this;

on(event: 'debug', listener: (msg: DebugMessage) => void): this;

on(event: 'newListener', listener: (event: string | symbol, listener: Function) => void): this;

on(event: 'removeListener', listener: (event: string | symbol, listener: Function) => void): this;

on(event: string, listener: void): this;