def start_subscriptions(subscriptions, options = {})
      details = subscriptions.map { |subscription| { subscription: subscription, action: :start, options: options } }

      perform_subscription_actions details
    end
def start_subscriptions(subscriptions, options = {})
      details = subscriptions.map { |subscription| { subscription: subscription, action: :start, options: options } }

      perform_subscription_actions details
    end
This method performs {Subscription#start} on all the passed subscriptions. Calling {Subscription#start} on each
 subscription individually would also work but requires a separate POST request to be sent for every subscription,
 whereas this method starts 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 start request, or `nil` if no error occurred.

 @param [Array<Subscription>] subscriptions The subscriptions to start.
 @param [Hash] options The options to start the subscriptions with. See {Subscription#start} for details on the
        supported options.

 @return [Array<LightstreamerError, nil>]