anchor.diff:  By default RailsEventStore will use `YAML` as a
   serialization format. The reason is that `YAML` is available out of box
   and can serialize and deserialize data types which are not easily
  -handled in other formats. As an example, `JSON` cannot out of box handle
  -deserializing dates. You get back `String` instead of a `Date`.
  +handled in other formats. 
   
   However, if you don't like `YAML` or you have different needs you can
  -choose to use different serializers (even whole mappers).
  +choose to use different serializers or even replace mappers entirely.
   
   ## Configuring a different serializer
   
  
positive.code: OrderPlaced = Class.new(MyEvent)
  ```
  
  That shields you from data keys being transformed from symbols into strings. It doesn't do anything with data values though so beware.
  
  ```ruby
  event_store.publish(OrderPlaced.new(event_id: 'e34fc19a-a92f-4c21-8932-a10f6fb2602b', data: { foo: :bar }))
  
negative.code: the client](/docs/install).
  
  Here is an example on how to configure RailsEventStore to serialize
  events' `data` and `metadata` using `Marshal`.
  
  ```ruby
  # config/environments/*.rb
  