Formats the duration as a base-10 integer.

    :param age: should be an integer number of seconds,
                a :class:`datetime.timedelta` object, or,
                if the age is unknown, `None` (default).

def dump_age(age=None):
    """Formats the duration as a base-10 integer.

    :param age: should be an integer number of seconds,
                a :class:`datetime.timedelta` object, or,
                if the age is unknown, `None` (default).
    """
    if age is None:
        return
    if isinstance(age, timedelta):
        # do the equivalent of Python 2.7's timedelta.total_seconds(),
        # but disregarding fractional seconds
        age = age.seconds + (age.days * 24 * 3600)

    age = int(age)
    if age < 0:
        raise ValueError("age cannot be negative")

    return str(age)