code: public int remove(Filter filter)
      {
          int size = trie.size();
          for (Map.Entry<String, V> entry : entrySet())
          {
              if (filter.remove(entry))
              {
                  trie.remove(entry.getKey());
              }
          }
  
          return size - trie.size();
      }
docs: 过滤部分词条
  @param filter 过滤器
  @return 删除了多少条