How to use RegisterCumulDependentTransitCallback in python?

[Grenby]

Hello!
I see that pywrapcp.RoutingModel contains RegisterCumulDependentTransitCallback.
Is it callback that support signature (index_a, index_b, cummul_var_a) ?
How I can create and use this callback in my model? I cant find any information about this.
For example I want to use piecewise linear cost for vehicles

Thanks for your advice

[lperron]

you cannot and you should not.
This part of the code is buggy and should not be used.

[0nyr]

To add one independent data point to Laurent's answer: we probed this API in depth (C++ side included) before finding this thread. The Python wheel cannot register the callback type at all (no SWIG typemap), and in C++ the engine stores registered callbacks without ever evaluating them during search or restoration, so the piecewise-linear part of such a dimension is silently dropped. Removal is announced in #5070. If what brought you here is actual time-dependent travel times, Kayros (MIT, pip install kayros) solves duration-minimization TDVRP(TW) over piecewise-linear arrival-time functions, with exact and anytime modes, a public checker and certified optima on MAMUT-routing.