How to use the fava.util.date.Interval function in fava

Args:
        custom_entries: the Custom entries to parse budgets from.

    Returns:
        A dict of accounts to lists of budgets.

    Example:
        2015-04-09 custom "budget" Expenses:Books "monthly" 20.00 EUR
    """

    budgets = defaultdict(list)
    errors = []

    interval_map = {
        "daily": Interval.DAY,
        "weekly": Interval.WEEK,
        "monthly": Interval.MONTH,
        "quarterly": Interval.QUARTER,
        "yearly": Interval.YEAR,
    }

    for entry in custom_entries:
        if entry.type == "budget":
            try:
                interval = interval_map.get(str(entry.values[1].value))
                if not interval:
                    errors.append(
                        BudgetError(
                            entry.meta,
                            "Invalid interval for budget entry",
                            entry,

interval: An interval.
        date: A date.

    Returns:
        A number, the number of days surrounding the given date in the
        interval.
    """

    if interval is Interval.DAY:
        return 1
    if interval is Interval.WEEK:
        return 7
    if interval is Interval.MONTH:
        date = datetime.date(date.year, date.month, 1)
        return (get_next_interval(date, Interval.MONTH) - date).days
    if interval is Interval.QUARTER:
        quarter = (date.month - 1) / 3 + 1
        date = datetime.date(date.year, int(quarter) * 3 - 2, 1)
        return (get_next_interval(date, Interval.QUARTER) - date).days
    if interval is Interval.YEAR:
        date = datetime.date(date.year, 1, 1)
        return (get_next_interval(date, Interval.YEAR) - date).days
    raise NotImplementedError

def get(string: str) -> enum.Enum:
        """Return the enum member for a string."""
        try:
            return Interval[string.upper()]
        except KeyError:
            return Interval.MONTH

# pylint: disable=too-many-return-statements
    try:
        if interval is Interval.YEAR:
            return datetime.date(date.year + 1, 1, 1)
        if interval is Interval.QUARTER:
            for i in [4, 7, 10]:
                if date.month < i:
                    return datetime.date(date.year, i, 1)
            return datetime.date(date.year + 1, 1, 1)
        if interval is Interval.MONTH:
            month = (date.month % 12) + 1
            year = date.year + (date.month + 1 > 12)
            return datetime.date(year, month, 1)
        if interval is Interval.WEEK:
            return date + datetime.timedelta(7 - date.weekday())
        if interval is Interval.DAY:
            return date + datetime.timedelta(1)
    except (ValueError, OverflowError):
        return datetime.date.max
    raise NotImplementedError

Args:
        custom_entries: the Custom entries to parse budgets from.

    Returns:
        A dict of accounts to lists of budgets.

    Example:
        2015-04-09 custom "budget" Expenses:Books "monthly" 20.00 EUR
    """

    budgets = defaultdict(list)
    errors = []

    interval_map = {
        "daily": Interval.DAY,
        "weekly": Interval.WEEK,
        "monthly": Interval.MONTH,
        "quarterly": Interval.QUARTER,
        "yearly": Interval.YEAR,
    }

    for entry in custom_entries:
        if entry.type == "budget":
            try:
                interval = interval_map.get(str(entry.values[1].value))
                if not interval:
                    errors.append(
                        BudgetError(
                            entry.meta,
                            "Invalid interval for budget entry",
                            entry,
                        )