register

# File activemodel/lib/active_model/type/registry.rb, line 15
      def register(type_name, klass = nil, &block)
        unless block_given?
          block = proc { |_, *args| klass.new(*args) }
          block.ruby2_keywords if block.respond_to?(:ruby2_keywords)
        end
        registrations[type_name] = block
      end