Why dict.totalFreq not reduce freq in RemoveToken

[zmq412]

if doing AddToken and RemoveToken a same word repeatedly，the totalFreq will increasingly larger。

[zhaomoqiang]

// AddToken add a token to the dictionary
func (dict *Dictionary) AddToken(token Token) error {
.......
dict.totalFreq += token.freq
......
return nil
}

// RemoveToken remove token in dictionary
func (dict *Dictionary) RemoveToken(token Token) error {
bytes := textSliceToBytes(token.text)
return dict.trie.Delete(bytes)
}