method_missing

# File actionpack/lib/action_controller/mime_type.rb, line 155
      def method_missing(method, *args)
        if method.to_s =~ /(\w+)\?$/
          mime_type = $1.downcase.to_sym
          mime_type == @symbol || (mime_type == :html && @symbol == :all)
        else
          super
        end
      end