首先:

def f():    print('first')def g():    f()g()def f():    print('second')g()

结果:

>>> firstsecond

 

又来:

def g():    f()g()def f():    print('second')g()

结果:

NameError: global name 'f' is not defined

 

再来:

def g():    f()def f():    print('second')g()

结果:

>>> second