'Mark every second in *bysecond*; *bysecond* can be an int or
sequence.  Default is to tick every second: ``bysecond = range(60)``
*interval* is the interval between each iteration.  For
example, if ``interval=2``, mark every second occurrence.'

def __init__(self, bysecond=None, interval=1, tz=None):

    if (bysecond is None):
        bysecond = range(60)
    rule = rrulewrapper(SECONDLY, bysecond=bysecond, interval=interval)
    RRuleLocator.__init__(self, rule, tz)
