# File lib/active_record/base.rb, line 557
      def serialize(attr_name, class_name = Object)
        coder = if [:load, :dump].all? { |x| class_name.respond_to?(x) }
                  class_name
                else
                  Coders::YAMLColumn.new(class_name)
                end

        # merge new serialized attribute and create new hash to ensure that each class in inheritance hierarchy
        # has its own hash of own serialized attributes
        self.serialized_attributes = serialized_attributes.merge(attr_name.to_s => coder)
      end