To be precise; with precision:

In C (and IIUC now Python, too), a stack frame is created for each function call (unless tail call optimization is applied by the compiler).

To avoid creating an unnecessary stack frame for each recursive function call, instead create a collections.deque and add traversed nodes to the beginning or end enqueued for processing in a loop within one non-recursive function.

Is Tail Call Optimization faster than collections.deque in a loop in one function scope stack frame?