code: public boolean isMatch() {
          if (shuntsuList.size() > 0) {
              return false;
          }
          for (Toitsu toitsu : toitsuList) {
              int num = toitsu.getTile().getNumber();
              if (1 < num && num < 9) {
                  return false;
              }
          }
  
          for (Kotsu kotsu : kotsuList) {
              int num = kotsu.getTile().getNumber();
              if (1 < num && num < 9) {
                  return false;
              }
          }
          return true;
      }
docs: 么九牌以外を見つけたらfalseを返す
  
  @return 混老頭かどうか