我希望我的代碼僅按字母順序輸出字符串中的每個(gè)字母一次，例如banana將輸出abn.問(wèn)題是我仍然需要它來(lái)計(jì)算字符串中每個(gè)字母的出現(xiàn)次數(shù)，所以輸出應(yīng)該如下：a occurs in the word banana a total of 3 times(s)b occurs in the word banana a total of 1 time(s)n occurs in the word banana a total of 2 time(s)...這是我的代碼：def letter_counter(string):    stg = string.lower()    stg = ''.join(sorted(stg))    for i in stg:        a = stg.count(i)        print(f'the letter {i} appears in the word {string} {a} times')            letter_counter('banana')而當(dāng)前的輸出如下：the letter a appears in the word banana 3 timesthe letter a appears in the word banana 3 timesthe letter a appears in the word banana 3 timesthe letter b appears in the word banana 1 timesthe letter n appears in the word banana 2 timesthe letter n appears in the word banana 2 times