code: def test_reg_splitter(dataset, splitter):
      model = tree.HoeffdingTreeRegressor(
          splitter=splitter,
          grace_period=20,
          delta=0.1,
          leaf_prediction="mean",
      )
  
      for x, y in dataset:
          model.learn_one(x, y)
  
      assert model.height > 0
  
file_path: river/river/tree/test_splitter.py
imports: from __future__ import annotations
  import pytest
  from river import datasets, tree
  from river.datasets import synth
label_desc: Use image node_id 3 for calling a global function with example usage: test_reg_splitter(dataset, splitter) without return types