def stop_subscriptions(subscriptions)
      details = subscriptions.map { |subscription| { subscription: subscription, action: :stop } }

      perform_subscription_actions details
    end
def stop_subscriptions(subscriptions)
      details = subscriptions.map { |subscription| { subscription: subscription, action: :stop } }

      perform_subscription_actions details
    end
This method performs {Subscription#stop} on all the passed subscriptions. Calling {Subscription#stop} on each
 subscription individually would also work but requires a separate POST request to be sent for every subscription,
 whereas this method stops all of the passed subscriptions in a single POST request which is significantly faster
 for a large number of subscriptions. The return value is an array with one entry per subscription and indicates
 the error state returned by the server for that subscription's stop request, or `nil` if no error occurred.

 @param [Array<Subscription>] subscriptions The subscriptions to stop.

 @return [Array<LightstreamerError, nil>]