code: private PassFactory getCustomPasses(final CustomPassExecutionTime executionTime) {
      return new PassFactory("runCustomPasses", true) {
        @Override
        protected CompilerPass create(final AbstractCompiler compiler) {
          return runInSerial(options.customPasses.get(executionTime));
        }
  
        @Override
        protected FeatureSet featureSet() {
          return ES_NEXT;
        }
      };
    }
docs: Runs custom passes that are designated to run at a particular time.
  
  <p>TODO(nickreid): Deprecate this API