请教大家一个问题

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#1 Created at ... [Delete] [Delete and Lock User]

def add_end(L=None): if L is None: L = [] L.append('END') return L add_end() 此时输出的结果为['end']

代码加一句

def add_end(L=None): if L is None: L = [] else:
L.append('END') return L

add_end() 此时输出结果为[]

请问第一个循环应该如何理解？只有if没有else吗？感谢大家

#2 Created at ... [Delete] [Delete and Lock User]

不需要else，L有值的时候直接加'END'，只有L为None的时候，才会初始货L=[]

#3 Created at ... [Delete] [Delete and Lock User]

好滴谢谢啦我再想一想