code: def test_memory_usage_multitarget():
      dataset = get_regression_data()
  
      model = tree.iSOUPTreeRegressor(
          leaf_prediction="mean",
          max_size=0.5,
          memory_estimate_period=100,
      )
  
      for x, y in dataset:
          # Handcrafted targets
          y_ = {0: y, 1: 2 * y, 2: 3 * y}
          model.learn_one(x, y_)
  
      assert model._raw_memory_usage / (2**20) < 0.5
  
file_path: river/river/tree/test_trees.py
imports: from __future__ import annotations
  import random
  import pytest
  from river import drift, tree
  from river.datasets import synth
label_desc: Use image node_id 5 for calling a global function with example usage: test_memory_usage_multitarget() without return types