    # File lib/rack/static.rb, line 109
        def call(env)
          path = env[PATH_INFO]

          if can_serve(path)
            env["PATH_INFO"] = (path =~ /\/$/ ? path + @index : @urls[path]) if overwrite_file_path(path)
            path = env["PATH_INFO"]
            response = @file_server.call(env)

            headers = response[1]
            applicable_rules(path).each do |rule, new_headers|
              new_headers.each { |field, content| headers[field] = content }
            end

            response
          else
            @app.call(env)
          end
        end