l = [
        {
            "dpt_id": 2,
            "domain_id": 2,
            "tag_id": 11,
            "wgt_val": 90.0
        },
        {
            "dpt_id": 46,
            "domain_id": 2,
            "tag_id": 12,
            "wgt_val": 15.0
        },
        {
            "dpt_id": 25,
            "domain_id": 4,
            "tag_id": 12,
            "wgt_val": 30.0
        },
        {
            "dpt_id": 107,
            "domain_id": 4,
            "tag_id": 12,
            "wgt_val": 70.0
        },
        {
            "dpt_id": 107,
            "domain_id": 3,
            "tag_id": 12,
            "wgt_val": 3330.0
        },
    ]

求dpt_id 相同的 wgt_val的 sum