Error if a key is substring of another key

[alessandro308]

Example:

unflatten(flatten({'a': '1', 'ab': 2, 'c': {'d': 4} }))
{'ab': 2, 'c': {'d': 4}}
expected result: {'a': '1', 'ab': 2, 'c': {'d': 4} }

[stanim]

I can't reproduce this with python 3.9.2:

>>> flatten_json.unflatten(flatten_json.flatten({'a': '1', 'ab': 2, 'c': {'d': 4} }))
{'a': '1', 'ab': 2, 'c': {'d': 4}}