python 递归

list2 = [11, 22, [33, 44], [55, [66, 77]], [88, [99, [100, [200, [300]]]]]]
list3=[11, 22, 33, 44, 55, 66, 77, 88, 99, 100, 200, 300]
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把list2转成list3
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def f(li):
    ret=[]
    for i in li:
        if isinstance(i,list):
            for j in f(i):
                ret.append(j)
        else:
            ret.append(i)
    return ret

print(f(list2))