```ruby

module Yarn
  module ErrorPage

    def serve_404_page
      @response.status = 404
      @response.body = ["<html><head><title>404</title></head><body><h1>File does not exist.</h1></body><html>"]
    end

    def serve_500_page
      @response.status = 500
      @response.body = ["<h1>Yarn!?</h1>\nA server error occured."]
    end

  end
end
```

Include filename in 404 message
user
```ruby

module Yarn
  module ErrorPage

    def serve_404_page
      @response.status = 404
      @response.body = ["<html><head><title>404</title></head><body><h1>File: #{@request[:uri][:path]} does not exist.</h1></body><html>"]
    end

    def serve_500_page
      @response.status = 500
      @response.body = ["<h1>Yarn!?</h1>\nA server error occured."]
    end

  end
end
```
assistant