请教大家一个关于时间的问题

CODE:

ISOTIMEFORMAT='%Y-%m-%d %X'
def time2sec( t ):
    '''
    把剩余的时间转换成秒
    '''
    return t

def ISOString2Time( s ):
    '''
    convert a ISO format time to second
    from:2006-04-12 16:46:40 to:23123123
    '''
    return time.strptime( s, ISOTIMEFORMAT )
def Time2ISOString( s ):
    '''
    convert second to a ISO format time
    from: 23123123 to: 2006-04-12 16:46:40
    '''
    return time.strftime( ISOTIMEFORMAT, time.localtime( float( s ) ) )
def dateplustime( d, t ):
    '''
    d=2006-04-12 16:46:40
    t=2小时
    return  2006-04-12 18:46:40
    '''
    return Time2ISOString( time.mktime( ISOString2Time( d ) )+time2sec( t ) )