Problem statement explain needed
[["a"],["a","t"],["a","t","y"],["a","z"],["b"],["b","x"],["b","x","y"],["b","z"]]\nWhy run this test return non empty result?\nI assume that t and x are identic
```[["a"],["a","t"],["a","t","y"],["a","z"],["b"],["b","x"],["b","x","y"],["b","z"]]```\nWhy run this test return non empty result?\nI assume that ```t``` and ```x``` are identical, so ```a``` and ```b``` should be identical (cause has same set of indetical subfolder as well)
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