    # File lib/active_support/core_ext/module/synchronization.rb, line 15
      def synchronize(*methods)
        options = methods.extract_options!
        unless options.is_a?(Hash) && with = options[:with]
          raise ArgumentError, "Synchronization needs a mutex. Supply an options hash with a :with key as the last argument (e.g. synchronize :hello, :with => :@mutex)."
        end

        methods.each do |method|
          aliased_method, punctuation = method.to_s.sub(/([?!=])$/, ''), $1

          if method_defined?("#{aliased_method}_without_synchronization#{punctuation}")
            raise ArgumentError, "#{method} is already synchronized. Double synchronization is not currently supported."
          end

          module_eval("def \#{aliased_method}_with_synchronization\#{punctuation}(*args, &block)     # def expire_with_synchronization(*args, &block)\n\#{with}.synchronize do                                                    #   @@lock.synchronize do\n\#{aliased_method}_without_synchronization\#{punctuation}(*args, &block)  #     expire_without_synchronization(*args, &block)\nend                                                                       #   end\nend                                                                         # end\n", __FILE__, __LINE__)

          alias_method_chain method, :synchronization
        end
      end