Custom c++ metric Run Problem

[gavrenkov]

Problem:
catboost version: 0.23.2
Operating System: all
Tutorial: https://github.com/catboost/tutorials/blob/master/custom_loss/custom_metric_tutorial.md

Impossible to use custom metric (С++).

Code example

from catboost import CatBoost
train_data = [[1, 4, 5, 6],
              [4, 5, 6, 7],
              [30, 40, 50, 60]]

eval_data = [[2, 4, 6, 8],
             [1, 4, 50, 60]]
train_labels = [10, 20, 30]
model = CatBoost(params={"loss_function":"UserPerObjMetric",'leaf_estimation_backtracking': 'No','eval_metric':'RMSE'})
model.fit(train_data, train_labels)
preds = model.predict(eval_data)