Interface WebSocketBackend

interface WebSocketBackend {
    close: (
        code?: number,
        reason?: string | Buffer<ArrayBufferLike>,
    ) => void;
    on: <T extends keyof WebSocketBackendEvents>(
        event: T,
        listener: WebSocketBackendEvents[T],
    ) => this;
    ping: (data?: any, mask?: boolean, cb?: (err: Error) => void) => void;
    send: (data: any, cb?: (err?: Error) => void) => void;
}