问请问tca考试第一次考试没过，补考需要在下个月时间考试，能不能现在又报名考试，在最短时间又考试呢？

def blank_fn(*args, **kwargs):
    pass

def perform_task(callback=None):
    print 'doing stuff'
    if callback is not None:
        callback('x', 'y', z='z')

def do_nothing(*args, **kwargs): pass
def do_something(arg, callback=do_nothing):
    a = 1 + 2
    callback('z', z='z')
def do_something_else(arg, callback=None):
    a = 1 + 2
    if callback is not None:
        callback('z', z='z')

%timeit do_something(3)
1000000 loops, best of 3: 644 ns per loop

%timeit do_something_else(3)
1000000 loops, best of 3: 292 ns per loop