Flatten flate strings as well

unlike the playground in python the flatten function flate the strings here the output from the playground vs the output from python of the same query and input data.
input:
["foo", "bar" , [{"text":"buz qux"}]]
query:
flatten() | filter(not(exists(.text)))
1 - playground:
["foo", "bar"]
2- python:
['f', 'o', 'o', 'b', 'a', 'r']

使用提供的输入和查询在 Python 实现中重现该问题，然后将其结果与 playground 的输出进行比较。跟踪 flatten() 如何处理字符串，并为此情况添加回归测试。当 Python 结果与 playground 一致时即完成：["foo", "bar"]。