pun_mutable:
        duration might be changed during runtime
    pun_round_to_next_24h_boundary
        duration has to be aligned with next possible 24h boundary
    pun_round_to_prev_24h_boundary
        duration has to be aligned with previous 24h boundary
    pun_align_with_timepoint
        duration has to be aligned with dedicated time point
Removed:
    pun_requires_change
        Replaced by pu_mutable