Accepts relative timestamp (`timedelta` or `timedelta`-supported ``dict``
    fmt), absolute `datetime`, or failbacks to `default`. Returns `datetime` (or
    `None` if `datetime` can not be derived from `ts`).

def absdatetime(ts, default=None):
    """Accepts relative timestamp (`timedelta` or `timedelta`-supported ``dict``
    fmt), absolute `datetime`, or failbacks to `default`. Returns `datetime` (or
    `None` if `datetime` can not be derived from `ts`)."""
    if ts is None:
        ts = default
    if isinstance(ts, dict):
        ts = timedelta(**ts)
    if isinstance(ts, timedelta):
        ts = now() + ts
    if isinstance(ts, datetime):
        return ts
    return None