Python ceil up or floor down datetime object to given resolution (not exceeding one day, with one second granularity)

round_dt.py

from datetime import timedelta
def ceil_dt(dt, res):
    # how many secs have passed this day
    nsecs = dt.hour*3600 + dt.minute*60 + dt.second + dt.microsecond*1e-6
    delta = res.seconds - nsecs % res.seconds
    if delta == res.seconds:
        delta = 0
    return dt + datetime.timedelta(seconds=delta)

def floor_dt(dt, res):
    # how many secs have passed this day
    nsecs = dt.hour*3600 + dt.minute*60 + dt.second + dt.microsecond*1e-6
    delta = nsecs % res.seconds
    return dt - datetime.timedelta(seconds=delta)