instance method draw

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 1611
        def draw(name)
          path = @draw_paths.find do |_path|
            File.exist? "#{_path}/#{name}.rb"
          end

          unless path
            msg  = "Your router tried to #draw the external file #{name}.rb,\n" \
                   "but the file was not found in:\n\n"
            msg += @draw_paths.map { |_path| " * #{_path}" }.join("\n")
            raise ArgumentError, msg
          end

          route_path = "#{path}/#{name}.rb"
          instance_eval(File.read(route_path), route_path.to_s)
        end