longest common prefix in a list of strings

longest_prefix.py

# longest_prefix.py

def longest_prefix(strings_list: list[str, ...]) -> str:
    if strings_list is None:
        return None
    if 0 == len(strings_list):
        return ""
    common_prefix = ""
    max_prefix_length = min(
        len(item)
        for item in strings_list
    )
    complete = False
    while not complete and len(common_prefix) < max_prefix_length:
        target_index = len(common_prefix)
        target_char = strings_list[0][target_index]
        for string_index in range(len(strings_list)):
            if strings_list[string_index][target_index] != target_char:
                complete = True
        if not complete:
            common_prefix = common_prefix + target_char
    return common_prefix


if __name__ == "__main__":
    test_data = [
        [],
        [""],
        ["", "abc"],
        ["abc", "abcdef"],
        ["this is a test!", "this is another test!"]
    ]
        for input_data in test_data:
        print("%s" % input_data)
        print("longest_prefix: %s" % longest_prefix(input_data))
        print()
    print()