我如何更改none并写入值?

你忘了 return token_score . 当任何函数未执行显式 return return None 已使用。

(更新)

def sentence_score(sentence_tokens, previous_token, acum_score):    
    if not sentence_tokens:
        return acum_score
    else:
        current_token = sentence_tokens[0]
        tags = current_token[2]
        token_score = sum([value(tag) for tag in tags])
        if previous_token is not None:
            previous_tags = previous_token[2]
            #print('token1', previous_tags)
            if 'inc' in previous_tags:
                token_score += 1.0
            elif 'dec' in previous_tags:
                token_score -= 1.0
            elif 'inv' in previous_tags:
                token_score -= 2
        return token_score