OP solved it, closing

My solution works but I'm not sure if it's correct to use 'sys.setrecursionlimit()' in Python.

I'm sure the level should be 4, but yes, there is a mistake in the string.

I'm sure that u are creating a new node with Node(pos), a node with default values like passable = True, to access to a node in the grid just pos.position or pos.passable.

The frequency of a character matters, if you have in the first string "aa" and the second string is "aaa" the programm should return FALSE. But if the first string is "bbb" and the second string is "bb" the programm should return TRUE.

Again, your code goes through all elements of a, what if a has a million elements and b another million? Think how you can possibly do less operations without going through all elements of each string.

Please take care not to post solutions in the discourse without the spoiler tag.

Change the algorithm, right now, it does a lot of unnecessary calculations.