anchor.diff:  
   ## Resources
   
  -There're already few blog posts about building an event sourced applications with [rails_event_store](https://github.com/RailsEventStore/rails_event_store) and `aggregate_root` gems:
  +There're already a few blog posts about building event sourced applications with [rails_event_store](https://github.com/RailsEventStore/rails_event_store) and `aggregate_root` gems:
   
   - [Why use Event Sourcing](https://blog.arkency.com/2015/03/why-use-event-sourcing/)
   - [The Event Store for Rails developers](https://blog.arkency.com/2015/04/the-event-store-for-rails-developers/)
  
positive.code: end
  ```
  
  The `apply_strategy` method must return a _callable_, that responds to `#call`. We've used lambda in the example above. This lambda takes two arguments -- `aggreate` which in this case is `self` and a an `event` being applied.
  
  The `case` statement is one way to implement such dispatch. The following example shows an equivalent implemented with `Hash`:
  
  ```ruby
  def apply_strategy
  
negative.code: end
  ```
  
  And then your code to submit an order might look like:
  
  ```ruby
  repository = OrderRepository.new
  