code: Action transform(int act)
      {
          if (act == 0)
          {
              return ActionFactory.make_shift();
          }
          else if (act < 1 + L)
          {
              return ActionFactory.make_left_arc(act - 1);
          }
          else if (act < 1 + 2 * L)
          {
              return ActionFactory.make_right_arc(act - 1 - L);
          }
          else
          {
              System.err.printf("unknown transition in transform(int): %d", act);
          }
          return new Action();
      }
docs: 转换动作id为动作
  @param act 动作类型的依存关系id
  @return 动作