convert numpy's datetime64 to datetime

def datetime64_to_datetime(dt):
    """ convert numpy's datetime64 to datetime """
    dt64 = np.datetime64(dt)
    ts = (dt64 - np.datetime64('1970-01-01T00:00:00')) / np.timedelta64(1, 's')
    return datetime.datetime.utcfromtimestamp(ts)