如何计算python中包含特定项的列表的项目总数

我想计算包含“a”的列表的项目总数，它应该是4+3=7

tweetword = (['a','b','c','a'],['a','e','f'],['d','g'])
count_total_a = {}
for t in tweetword:
    for word in tweetword:
        if word not in count_total_a:
            count_toal_a[word] = len(t)
        if word in count_total_a:
            count_total_a[word] += len(t)
'''the result I get is not correct coz it counts the first list twice'''

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非常感谢您的帮助

取发电机上的总和：

tweetword = (['a','b','c','a'],['a','e','f'],['d','g'])

contains_a = [tweet for tweet in tweetword if 'a' in tweet]

sum_lengths = sum(map(len, contains_a))

print(sum_lengths)

sum(len(x) for x in tweetword if 'a' in x)