# File lib/active_support/callbacks.rb, line 619
      def define_callbacks(*callbacks)
        config = callbacks.last.is_a?(Hash) ? callbacks.pop : {}
        callbacks.each do |callback|
          class_attribute "_#{callback}_callbacks"
          send("_#{callback}_callbacks=", CallbackChain.new(callback, config))
          __define_runner(callback)
        end
      end