请教代码执行顺序的问题

from types import FunctionType def tracer(func): calls = 0 def onCall(*args, **kwargs): nonlocal calls calls += 1 print('call %s to %s' % (calls, func.__name__)) #语句 1 return func(*args, **kwargs) #语句 2 return onCall class MetaTrace(type): def __new__(meta, classname, supers, classdict): for attr, attrval in classdict.items(): print('attr=%s ,attrval=%s'%(attr,attrval)) if type(attrval) is FunctionType: classdict[attr] = tracer(attrval) #语句 3 return type.__new__(meta, classname, supers, classdict) class Person(metaclass=MetaTrace): def __init__(self, name, pay): print("Person init,name=",name) self.name = name self.pay = pay def giveRaise(self, percent): print("Person giveRaise,percent=",percent) self.pay *= (1.0 + percent) def lastName(self): print("Person lastName,self=",self) return self.name.split()[-1] print('-----------------') bob = Person('Bob Smith', 50000) 上面代码输出如下： attr=__module__ ,attrval=__main__ attr=__qualname__ ,attrval=Person attr=__init__ ,attrval=<function Person.__init__ at 0x01C2BBB8> attr=giveRaise ,attrval=<function Person.giveRaise at 0x01C2BB70> attr=lastName ,attrval=<function Person.lastName at 0x01C2BB28> ----------------- call 1 to __init__ Person init,name= Bob Smith 我的问题是： 执行语句 3 时，当执行到 classdict[__init__] = tracer(<function Person.__init__ at 0x01C2BBB8>) 时，为何不会立即去执行 tracer 定义中的语句 1 和语句 2，使得__init__方法的结果赋值给 classdict[__init__] ？