多謝版友解釋，原T1 decorator產生出來的是class
結果跟下面差不多，因為func不是function，所以
不會變成method，所以也就不會自動帶入self.
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class T1(object): pass
class A(object):
def f(self): pass
print(type(f)) # <class 'function'>
func = T1()
print(type(func)) # <class '__main__.T1'>
a = A()
print(type(a.f)) # <class 'method'>
print(type(a.func)) # <class '__main__.T1'>
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