rotation (Rack::Reloader::Stat)

    # File lib/rack/reloader.rb, line 65
          def rotation
            files = [$0, *$LOADED_FEATURES].uniq
            paths = ['./', *$LOAD_PATH].uniq

            files.map{|file|
              next if file =~ /\.(so|bundle)$/ # cannot reload compiled files

              found, stat = figure_path(file, paths)
              next unless found and stat and mtime = stat.mtime

              @cache[file] = found

              yield(found, mtime)
            }.compact
          end