Python处理二维列表里相同项则合并

[['abc',6],['bcd',3],['bcd',2]]->[['abc',6],['bcd',5]]

list1 = [['abc',6],['bcd',3],['bcd',2]]
dic = {}
for item in list1:
    if item[0] not in dic:
        dic[item[0]] = item[1]
    else:
        dic[item[0]] += item[1]
list_new = [[x,y] for x,y in dic.items()]