@CheckiO@The Most Wanted Letter

def checkio(text: str) -> str:

    #replace this for solution
    import re
    letter = []
    text = text.lower()
    for c in text:
        m = re.match(r'[a-z]', c)
        if m is None:
            continue
        else:
            letter.append(c)
    list_zero = []
    set_letter = set(letter)
    length = len(set_letter)
    for _ in range(length):
        list_zero.append(0)
    list_letter = list(set_letter)
    letter_dict = dict(zip(list_letter, list_zero))
    for c in letter:
        letter_dict[c] = letter_dict[c] + 1
    dict_sorted = sorted(letter_dict.items(), key=lambda x: (-x[1], x[0]))
    return dict_sorted[0][0]


if __name__ == '__main__':
    print("Example:")
    print(checkio("Hello World!"))

    #These "asserts" using only for self-checking and not necessary for auto-testing
    assert checkio("Hello World!") == "l", "Hello test"
    assert checkio("How do you do?") == "o", "O is most wanted"
    assert checkio("One") == "e", "All letter only once."
    assert checkio("Oops!") == "o", "Don't forget about lower case."
    assert checkio("AAaooo!!!!") == "a", "Only letters."
    assert checkio("abe") == "a", "The First."
    print("Start the long test")
    assert checkio("a" * 9000 + "b" * 1000) == "a", "Long."
    print("The local tests are done.")