```ruby
module Frankie
  class App
    extend ClassLevelApi

    RouteNotFoundError = Class.new StandardError
    RES_NOT_FOUND = Response.new '', 404

    def initialize app=nil
      @app = app
      build_middleware_chain
    end

    def build_middleware_chain
      @top = self.class.middlewares.reverse.reduce (self) do |prev, entry|
        klass, args, blk = entry
        klass.new prev, *args, &blk
      end
    end

    def self.run! port=9292
      use Rack::ShowExceptions
      use Rack::CommonLogger
      handler = Rack::Handler::Thin rescue Rack::Handler::WEBrick
      handler.run new, :Port => port
    end

    def handler_for_path method, path
      self.class.routes.fetch(method.downcase.to_sym).each do |sig, h|
        params = sig.match path
        return [h, params] if params
      end

      raise RouteNotFoundError
    end

    def route req
      begin
        handler, params = handler_for_path req.request_method, req.path
        req.params.merge! params unless params.empty?
        RequestScope.new(self, req).apply_to &handler
      rescue KeyError, RouteNotFoundError
        if @app
          @app.call(req.env)
        else
          RES_NOT_FOUND
        end
      end
    end

    def _call env
      route Request.new(env)
    end

    def call env
      if @top == self
        _call env
      else
        if not @initialized_chain
          @initialized_chain = true
          @top.call(env)
        else
          @initialized_chain = false
          _call env
        end
      end
    end
  end
end
```

Add the default middleware on top os the stack
user
```ruby
module Frankie
  class App
    extend ClassLevelApi

    RouteNotFoundError = Class.new StandardError
    RES_NOT_FOUND = Response.new '', 404

    def initialize app=nil
      @app = app
      build_middleware_chain
    end

    def build_middleware_chain
      @top = self.class.middlewares.reverse.reduce (self) do |prev, entry|
        klass, args, blk = entry
        klass.new prev, *args, &blk
      end
    end

    def self.run! port=9292
      middlewares.unshift Rack::ShowExceptions, Rack::CommonLogger

      handler = Rack::Handler::Thin rescue Rack::Handler::WEBrick
      handler.run new, :Port => port
    end

    def handler_for_path method, path
      self.class.routes.fetch(method.downcase.to_sym).each do |sig, h|
        params = sig.match path
        return [h, params] if params
      end

      raise RouteNotFoundError
    end

    def route req
      begin
        handler, params = handler_for_path req.request_method, req.path
        req.params.merge! params unless params.empty?
        RequestScope.new(self, req).apply_to &handler
      rescue KeyError, RouteNotFoundError
        if @app
          @app.call(req.env)
        else
          RES_NOT_FOUND
        end
      end
    end

    def _call env
      route Request.new(env)
    end

    def call env
      if @top == self
        _call env
      else
        if not @initialized_chain
          @initialized_chain = true
          @top.call(env)
        else
          @initialized_chain = false
          _call env
        end
      end
    end
  end
end
```
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