code: def __init__(self, *args, **kwargs):
      super().__init__(*args, **kwargs)
  
      self.n_samples = 0
      self.mean = stats.Mean()
  
imports: from __future__ import annotations
  import collections
  import math
  from river import base, stats
  from river.tree.base import Branch, Leaf
  from river.utils.math import log_sum_2_exp
label_desc: Use image node_id 1 to create a new MondrianNodeRegressor object from inherited base classes: MondrianNode with example: obj = MondrianNodeRegressor()