有几条拦路的

按评审模型，四条意见的 severity 是 nit/block/suggest/block，blocking 交回几？

贯穿本节的评审意见模型：一条意见是 dict(suggestion, reason, severity)。is_constructive=既给了具体建议又说了为什么；severity ∈ {nit, suggest, block}，blocking(意见表) 数几条 block；can_merge(意见表, 批准数)=有人批准且没有 block。

def is_constructive(comment):
    # 建设性意见：既给了具体建议、又说了为什么
    return comment.get("suggestion", False) and comment.get("reason", False)


def blocking(comments):
    # 数有几条「拦路」的意见（severity == "block"）
    return sum(1 for c in comments if c.get("severity") == "block")


def can_merge(comments, approvals):
    # 有人批准、且没有拦路意见，才能合
    return approvals >= 1 and blocking(comments) == 0

cs = [{"severity": "nit"}, {"severity": "block"}, {"severity": "suggest"}, {"severity": "block"}]
print(blocking(cs))