Python嵌套字典求和：如何填充overall节点的汇总数据

我正在开发一个用于整合多源数据做分析的程序，目前有如下嵌套结构的字典：

output = {
    "main": {
        "overall": {
            "overall": {
                "total": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Profit": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Loss": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
            },
            "Sub A": {
                "total": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Profit": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Loss": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
            },
            "Sub B": {
                "total": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Profit": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Loss": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
            },
        },
        "A": {
            "overall": {
                "total": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Profit": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Loss": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
            },
            "Sub A": {
                "total": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Profit": {"q1": 10,"q2": 8,"q3": 19,"q4": 7},
                "Loss": {"q1": 4,"q2": 2,"q3": 6,"q4": 10},
            },
            "Sub B": {
                "total": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Profit": {"q1": 50,"q2": 70,"q3": 54,"q4": 77},
                "Loss": {"q1": 2,"q2": 8,"q3": 5,"q4": 40},
            },
        },
        "B": {
            "overall": {
                "total": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Profit": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Loss": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
            },
            "Sub A": {
                "total": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Profit": {"q1": 75,"q2": 23,"q3": 25,"q4": 12},
                "Loss": {"q1": 64,"q2": 22,"q3": 12,"q4": 5},
            },
            "Sub B": {
                "total": {"q1": 0,"q2": 0,"q3": 0,"q4": 0},
                "Profit": {"q1": 65,"q2": 53,"q3": 3,"q4": 5},
                "Loss": {"q1": 10,"q2": 12,"q3": 1,"q4": 2},
            },
        }
    }
}

目前非overall节点的Profit和Loss已有数据，需要编写函数完成以下填充：

• 所有节点的total：对应季度的Profit与Loss之和
• 所有overall节点的Profit：对应层级下所有Sub节点同季度Profit的累加值
• 所有overall节点的Loss：对应层级下所有Sub节点同季度Loss的累加值

我参考相关问题写出了如下函数，希望得到完善建议：

def calculateOveralls(dictionary, query):
    for a in dictionary[query]: #A,B,overall
        for b in dictionary[query][a]: #Sub A, Sub B, overall
            if b == "overall":
                pass
            else:
                for c in dictionary[query][a][b]:  # Profit/Loss
                    if c == "total":
                        pass
                    else:
                        for d in dictionary[query][a][b][c]:  # quarters
                            dictionary[query][a][b]["total"][d] = dictionary[query][a][b]["total"][d] + dictionary[query][a][b][c][d]

内容的提问来源于stack exchange，提问作者TIC-FLY