The notebook example is not working

I tried to run the notebook example with the following code snippet:

shap_explainer = fasttreeshap.TreeExplainer(lgb_model)
num_leaves = sum(shap_explainer.model.num_nodes) - sum(sum(shap_explainer.model.children_left > 0))
print("Total number of leaves is {}.".format(num_leaves))

But got the error:

AttributeError                            Traceback (most recent call last)
<command-4123838717328114> in <cell line: 2>()
      1 shap_explainer = fasttreeshap.TreeExplainer(lgb_model)
----> 2 num_leaves = sum(shap_explainer.model.num_nodes) - sum(sum(shap_explainer.model.children_left > 0))
      3 print("Total number of leaves is {}.".format(num_leaves))

AttributeError: 'TreeEnsemble' object has no attribute 'num_nodes'

The lightbgm library version is '3.3.5'. Maybe you want to update the notebook correspondingly.

Individua l'esempio di notebook che contiene lo snippet mostrato di TreeExplainer e num_leaves, quindi riproduci l'AttributeError con LightGBM 3.3.5. Aggiorna l'esempio in modo che venga eseguito con quella versione e verifica che il notebook venga completato riportando il numero totale di foglie.