docstr: The total number of instances processed by the ensemble.
code: def total_instances(self) -> float:
      """The total number of instances processed by the ensemble."""
      return self._total_instances
  
imports: from __future__ import annotations
  import abc
  import collections
  import math
  import random
  import sys
  from river import base, drift, metrics, tree, utils
  from river.tree.nodes.et_nodes import ETLeafAdaptive, ETLeafMean, ETLeafModel
  from river.tree.splitter.random_splitter import RegRandomSplitter
label_desc: Use image node_id 16 for calling the ExtraTrees obj's underlying member method code with example usage: obj.total_instances() and returns: self