'Set the timezone offset from UTC.
Arguments:
value -- Either a tzinfo object or the number of
seconds (positive or negative) to offset.'

def set_tzo(self, value):

    time = xep_0082.time(offset=value)
    if (xep_0082.parse(time).tzinfo == tzutc()):
        self._set_sub_text('tzo', 'Z')
    else:
        self._set_sub_text('tzo', time[(-6):])
