Access objective function from python

Dear experts,

I am trying to implement a custom objective function (focal loss) on xgboost and to make sure I got it right I would like to compare it against the normal logistic objective. How do I access the such function? Where do I find it?


All existing objectives are implemented in C++. See

forgive my naivete- how would i call it from python? would i need to write a custom wrapper?