def convert_to_datetime(input, tz, arg_name):
    """
    Converts the given object to a timezone aware datetime object.

    If a timezone aware datetime object is passed, it is returned unmodified.
    If a native datetime object is passed, it is given the specified timezone.
    If the input is a string, it is parsed as a datetime with the given timezone.

    Date strings are accepted in three different forms: date only (Y-m-d), date with time
    (Y-m-d H:M:S) or with date+time with microseconds (Y-m-d H:M:S.micro).

    :param str|datetime input: the datetime or string to convert to a timezone aware datetime
    :param datetime.tzinfo tz: timezone to interpret ``input`` in
    :param str arg_name: the name of the argument (used in an error message)
    :rtype: datetime

    """
    if input is None:
        return
    elif isinstance(input, datetime):
        datetime_ = input
    elif isinstance(input, date):
        datetime_ = datetime.combine(input, time())
    elif isinstance(input, six.string_types):
        m = _DATE_REGEX.match(input)
        if not m:
            raise ValueError('Invalid date string')
        values = [(k, int(v or 0)) for k, v in m.groupdict().items()]
        values = dict(values)
        datetime_ = datetime(**values)
    else:
        raise TypeError('Unsupported type for %s: %s' % (arg_name, input.__class__.__name__))

    if datetime_.tzinfo is not None:
        return datetime_
    if tz is None:
        raise ValueError(
            arg_name % 'The "tz" argument must be specified if %s has no timezone information')
    if isinstance(tz, six.string_types):
        tz = timezone(tz)

    try:
        return tz.localize(datetime_, is_dst=None)
    except AttributeError:
        raise TypeError(
            'Only pytz timezones are supported (need the localize() and normalize() methods)')
dataset/ETHPy150Open agronholm/apscheduler/apscheduler/util.py/convert_to_datetime/swapped operands of `%`