如何取消嵌套混合类型的元组?

How do I unnest a tuple with mixed types?

我正在尝试将具有混合类型的元组展平到列表中。以下函数未产生所需的输出:

a = (1, 2, 3, ['first', 'second'])
def flatten(l): 
return flatten(l[0]) + (flatten(l[1:]) if len(l) > 1 else []) if type(l) is list else [l]

>>> flatten(a)
[(1, 2, 3, ['first', 'second'])]
>>> flatten(flatten(a))
[(1, 2, 3, ['first', 'second'])]
>>> [flatten(item) for item in a]
[[1], [2], [3], ['first', 'second']]

输出应该是:

>>> [1, 2, 3, 'first', 'second']
def flatten(l):
    if isinstance(l, (list,tuple)):
        if len(l) > 1:
            return [l[0]] + flatten(l[1:])
        else:
            return l[0]
    else:
        return [l]

a = (1, 2, 3, ['first', 'second'])

print(flatten(a))

[1, 2, 3, 'first', 'second']