code: function (less, pluginManager) {
          var injector = this.getInstance(less);
  
          // only auto inject after 2.4.0
          if (pluginManager.addPreProcessor) {
              pluginManager.addPreProcessor(injector);
          }
      }
docs: Installation
  @param {Object} less the less.js instance
  @param {Object} pluginManager less.js plugin manager instance