python当中如果有一个列表里面是多个字典，且有一对键值对相同，想要求不同的键对应的值之和

a = [{"id":1,"count":29},{"id':1,"count":39}]

ids = list(set([u["id"] for u in a]))   #  [1,]

b = []
for id in ids:
    count = 0
    for u in a:
        if id in u.get('id'):
            count+= count
        b.append({"id':id,"count":count})

print(b)  #   [{"id":1,"count":68}]