public class ConfigurableResponseProcessor : IResponseProcessor
    {
        private Func<MediaRange, object, NancyContext, ProcessorMatch> canProcess = (media, model, context) => new ProcessorMatch();
        private Func<MediaRange, object, NancyContext, Response> process = (media, model, context) => 200;
        private IList<Tuple<string, MediaRange>> extensionMappings = new List<Tuple<string, MediaRange>>();

        public ConfigurableResponseProcessor()
        {
        }

        public ConfigurableResponseProcessor(Action<ConfigurableResponseProcessorConfigurator> action)
        {
            var configurator =
                new ConfigurableResponseProcessorConfigurator(this);

            action.Invoke(configurator);
        }

        public IEnumerable<Tuple<string, MediaRange>> ExtensionMappings
        {
            get { return this.extensionMappings; }
        }

        public ProcessorMatch CanProcess(MediaRange requestedMediaRange, dynamic model, NancyContext context)
        {
            return this.canProcess.Invoke(requestedMediaRange, model, context);
        }

        public Response Process(MediaRange requestedMediaRange, dynamic model, NancyContext context)
        {
            return this.process.Invoke(requestedMediaRange, model, context);
        }

        public class ConfigurableResponseProcessorConfigurator
        {
            private readonly ConfigurableResponseProcessor processor;

            public ConfigurableResponseProcessorConfigurator(ConfigurableResponseProcessor processor)
            {
                this.processor = processor;
            }

            public ConfigurableResponseProcessorConfigurator Extension(string extension, MediaRange range)
            {
                this.processor.extensionMappings.Add(new Tuple<string, MediaRange>(extension, range));
                return this;
            }

            public ConfigurableResponseProcessorConfigurator Extension(Tuple<string, MediaRange> mapping)
            {
                this.processor.extensionMappings.Add(mapping);
                return this;
            }

            public ConfigurableResponseProcessorConfigurator Extension(IEnumerable<Tuple<string, MediaRange>> mappings)
            {
                this.processor.extensionMappings = mappings.ToList();
                return this;
            }

            public ConfigurableResponseProcessorConfigurator CanProcess(Func<MediaRange, object, NancyContext, ProcessorMatch> action)
            {
                this.processor.canProcess = action;
                return this;
            }

            public ConfigurableResponseProcessorConfigurator Process(Func<MediaRange, object, NancyContext, Response> action)
            {
                this.processor.process = action;
                return this;
            }
        }
    }