# File lib/action_controller/dispatcher.rb, line 38
      def to_prepare(identifier = nil, &block)
        @prepare_dispatch_callbacks ||= ActiveSupport::Callbacks::CallbackChain.new
        callback = ActiveSupport::Callbacks::Callback.new(:prepare_dispatch, block, :identifier => identifier)
        @prepare_dispatch_callbacks.replace_or_append!(callback)
      end