    # File lib/rack/static.rb, line 83
        def initialize(app, options={})
          @app = app
          @urls = options[:urls] || ["/favicon.ico"]
          @index = options[:index]
          root = options[:root] || Dir.pwd

          # HTTP Headers
          @header_rules = options[:header_rules] || []
          # Allow for legacy :cache_control option while prioritizing global header_rules setting
          @header_rules.insert(0, [:all, {'Cache-Control' => options[:cache_control]}]) if options[:cache_control]

          @file_server = Rack::File.new(root)
        end