code: def n_leaves_functional(model: SklearnModel, sample: Model, X, y):
      n_leaves = 0
      for tree in sample.trees:
          n_leaves += len(tree.leaf_nodes)
      return n_leaves / len(sample.trees)
  
imports: import argparse
  import itertools
  import os
  from functools import partial
  import numpy
  import pandas
  import matplotlib.pyplot
  from matplotlib import cm
  from tqdm import tqdm
  from sklearn import model_selection, datasets
  from sklearn.metrics import mean_squared_error
  from imodels import get_clean_dataset
  from imodels.experimental.bartpy.model import Model
  from imodels.experimental.bartpy.tree import Tree
  from ..sklearnmodel import BART, SklearnModel
label_desc: Use image node_id 3 for calling a global function with example usage: n_leaves_functional(model, sample, X, y) and returns: unknown