如何对第一个值相同的列表中的元组求和

from collections import Counter
dict_test = Counter()
list_test = [('AAPL', 10), ('AAPL', 30), ('RY', 100), ('RY', 43)]
for key, val in list_test:
    dict_test[key] += val
    print(key)
    print(val)
print(dict_test)
print(dict_test.keys())
print(dict_test.values())