instance method i18n_keys

# File activemodel/lib/active_model/naming.rb, line 226
      def i18n_keys
        @i18n_keys ||= if @klass.respond_to?(:lookup_ancestors)
          # Anonymous ancestors have no model name to derive a key from, so
          # skip them rather than letting Name.new raise on their blank name.
          @klass.lookup_ancestors.filter_map do |klass|
            klass.model_name.i18n_key unless klass.name.blank?
          end
        else
          []
        end
      end