```ruby
# encoding: utf-8

require 'monitor'

module FiniteMachine
  # A class responsibile for storage of event subscribers
  class Subscribers
    include Enumerable
    include MonitorMixin

    # Initialize a subscribers collection
    #
    # @api public
    def initialize
      super
      @subscribers = []
    end

    # Iterate over subscribers
    #
    # @api public
    def each(&block)
      @subscribers.each(&block)
    end

    # Return index of the subscriber
    #
    # @api public
    def index(subscriber)
      @subscribers.index(subscriber)
    end

    # Check if anyone is subscribed
    #
    # @return [Boolean]
    #
    # @api public
    def empty?
      @subscribers.empty?
    end

    # Add listener to subscribers
    #
    # @param [Array[#trigger]] observers
    #
    # @return [undefined]
    #
    # @api public
    def subscribe(*observers)
      synchronize do
        observers.each { |observer| @subscribers << observer }
      end
    end

    # Visit subscribers and notify
    #
    # @param [HookEvent] hook_event
    #   the callback event to notify about
    #
    # @return [undefined]
    #
    # @api public
    def visit(hook_event)
      each { |subscriber| synchronize { hook_event.notify(subscriber) } }
    end

    # Number of subscribed listeners
    #
    # @return [Integer]
    #
    # @api public
    def size
      synchronize { @subscribers.size }
    end

    # Reset subscribers
    #
    # @return [self]
    #
    # @api public
    def reset
      @subscribers.clear
      self
    end
  end # Subscribers
end # FiniteMachine
```

Change subscirbers to be notified with data.
user
```ruby
# encoding: utf-8

require 'monitor'

module FiniteMachine
  # A class responsibile for storage of event subscribers
  class Subscribers
    include Enumerable
    include MonitorMixin

    # Initialize a subscribers collection
    #
    # @api public
    def initialize
      super
      @subscribers = []
    end

    # Iterate over subscribers
    #
    # @api public
    def each(&block)
      @subscribers.each(&block)
    end

    # Return index of the subscriber
    #
    # @api public
    def index(subscriber)
      @subscribers.index(subscriber)
    end

    # Check if anyone is subscribed
    #
    # @return [Boolean]
    #
    # @api public
    def empty?
      @subscribers.empty?
    end

    # Add listener to subscribers
    #
    # @param [Array[#trigger]] observers
    #
    # @return [undefined]
    #
    # @api public
    def subscribe(*observers)
      synchronize do
        observers.each { |observer| @subscribers << observer }
      end
    end

    # Visit subscribers and notify
    #
    # @param [HookEvent] hook_event
    #   the callback event to notify about
    #
    # @return [undefined]
    #
    # @api public
    def visit(hook_event, *data)
      each { |subscriber|
        synchronize { hook_event.notify(subscriber, *data) }
      }
    end

    # Number of subscribed listeners
    #
    # @return [Integer]
    #
    # @api public
    def size
      synchronize { @subscribers.size }
    end

    # Reset subscribers
    #
    # @return [self]
    #
    # @api public
    def reset
      @subscribers.clear
      self
    end
  end # Subscribers
end # FiniteMachine
```
assistant