code: private static CompilerPass runInSerial(
        final Collection<CompilerPass> passes) {
      return new CompilerPass() {
        @Override public void process(Node externs, Node root) {
          for (CompilerPass pass : passes) {
            pass.process(externs, root);
          }
        }
      };
    }
docs: Create a compiler pass that runs the given passes in serial.