anchor.diff:    - constructor takes named arguments:
       - `serializer:` (described above)
       - `events_class_remapping:` - which can be used for mapping old event names to new ones after you refactored your codebase.
  -- [`RubyEventStore::Mappers::Protobuf`](https://github.com/RailsEventStore/rails_event_store/blob/master/contrib/ruby_event_store-protobuf/lib/ruby_event_store/mappers/protobuf.rb)
  +- [`RubyEventStore::Mappers::Protobuf`](https://github.com/RailsEventStore/rails_event_store/blob/master/ruby_event_store/lib/ruby_event_store/mappers/protobuf.rb)
     - works with Ruby classes generated by `google-protobuf` gem
  -  - defined in `ruby_event_store-protobuf` gem
   - [`RubyEventStore::Mappers::NullMapper`](https://github.com/RailsEventStore/rails_event_store/blob/master/ruby_event_store/lib/ruby_event_store/mappers/null_mapper.rb)
     - works with `RubyEventStore::Event` or `RailsEventStore::Event`
     - no transformations, useful in tests
  
positive.code: the client](/docs/v1/install).
  
  Here is an example on how to configure RailsEventStore to serialize
  events' `data` and `metadata` using `JSON`.
  
  ```ruby
  # config/environments/*.rb
  
negative.code: end
  
  OrderPlaced = Class.new(MyEvent)
  </code>
  </pre>
  </div>
  
  That shields you from data keys being transformed from symbols into strings. It doesn't do anything with data values associated to those keys.
  
  <div class="highlight">
  <pre class="syntax-highlight ruby">
  <code>
  event_store.publish(OrderPlaced.new(event_id: 'e34fc19a-a92f-4c21-8932-a10f6fb2602b', data: { foo: :bar }))
  event = event_store.read.event('e34fc19a-a92f-4c21-8932-a10f6fb2602b')
  
  