def format_date(date=None, format='medium', locale=LC_TIME):
    """Return a date formatted according to the given pattern.

    >>> d = date(2007, 04, 01)
    >>> format_date(d, locale='en_US')
    u'Apr 1, 2007'
    >>> format_date(d, format='full', locale='de_DE')
    u'Sonntag, 1. April 2007'

    If you don't want to use the locale default formats, you can specify a
    custom date pattern:

    >>> format_date(d, "EEE, MMM d, ''yy", locale='en')
    u"Sun, Apr 1, '07"

    :param date: the ``date`` or ``datetime`` object; if `None`, the current
                 date is used
    :param format: one of "full", "long", "medium", or "short", or a custom
                   date/time pattern
    :param locale: a `Locale` object or a locale identifier
    """
    if date is None:
        date = date_.today()
    elif isinstance(date, datetime):
        date = date.date()

    locale = Locale.parse(locale)
    if ('full', 'long', 'medium', 'short') in format:
        format = get_date_format(format, locale=locale)
    pattern = parse_pattern(format)
    return pattern.apply(date, locale)
dataset/ETHPy150Open maraoz/proofofexistence/babel/dates.py/format_date/swapped operands of `in`