code: function(less) {
      this.less = less;
      this.visitors = [];
      this.preProcessors = [];
      this.postProcessors = [];
      this.installedPlugins = [];
      this.fileManagers = [];
      this.iterator = -1;
      this.pluginCache = {};
      this.Loader = new less.PluginLoader(less);
  }
docs: Plugin Manager