class ActiveModelSerializers::FragmentCache

def cache_attributes(serializers)

3. Add non-cached attributes to non-cached Serializer
2. Add cached attributes to cached Serializer
1. Determine cached attributes from serializer class options
Given a hash of its cached and non-cached serializers 
def cache_attributes(serializers)
  klass                 = serializer.class
  attributes            = klass._attributes
  cache_only            = klass._cache_only
  cached_attributes     = cache_only ? cache_only : attributes - klass._cache_except
  non_cached_attributes = attributes - cached_attributes
  attributes_keys       = klass._attributes_keys
  add_attributes_to_serializer(serializers[:cached], cached_attributes, attributes_keys)
  add_attributes_to_serializer(serializers[:non_cached], non_cached_attributes, attributes_keys)
end