<commit_before><commit_msg>"Add 20150511 question."<commit_after># solution 1
def special_single_number_1(lst):
    ht = {}                          # a hash map
    ht = defaultdict(lambda: 0, ht)  # with default value 0
    for i in lst:
        ht[i] += 1
    ret = []
    for k, v in ht.iteritems():
        if v == 1:
            ret.append(k)
    return ret
{'fraction_non_alphanumeric': 0.11570247933884298, 'fraction_numerical': 0.03856749311294766, 'mean_word_length': 1.8661417322834646, 'pattern_counts': {'":': 0, '<': 3, '<?xml version=': 0, '>': 3, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 1, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
{'dir': 'git-commits-cleaned', 'id': '2338895', 'n_tokens_mistral': 134, 'n_tokens_neox': 119, 'n_words': 37}