def string_list_to_string(stringli, sep=''):
    """列表转字符串
    :param stringli:
    :param sep:
    :return:
    >>> string_list_to_string(['1', '2', '3', '4', '5'])
    '12345'
    >>> string_list_to_string(['1', '2', '3', '4', '5'], '.')
    '1.2.3.4.5'
    >>> string_list_to_string(['1', '2', '3', '4', '5'], ' ')
    '1 2 3 4 5'
    """
    return sep.join(stringli)