python中rack中的拼写单词组合

from itertools import permutations

def generate_words(letters):
    words = []
    for i in range(1, len(letters)+1):
        perms = permutations(letters, i)
        for perm in perms:
            word = ''.join(perm)
            words.append(word)
    return words

rack = "rack"
word_combinations = generate_words(rack)
print(word_combinations)

['r', 'a', 'c', 'k', 'ra', 'rk', 'rc', 'rk', 'ra', 'rc', 'kr', 'ka', 'kc', 'kr', 'ka', 'kc', 'ar', 'ak', 'ac', 'ar', 'ak', 'ac', 'cr', 'ck', 'ca', 'cr', 'ck', 'ca', 'rk', 'ra', 'rc', 'rk', 'ra', 'rc', 'kar', 'kac', 'kra', 'krc', 'kar', 'kac', 'kra', 'krc', 'ka...]