code: def proxy_impurity_improvement(self):
      impurity_left = 0.0
      impurity_right = 0.0
      impurity_left, impurity_right = self.children_impurity(
          impurity_left, impurity_right
      )
  
      return (
          -self.weighted_n_right * impurity_right
          - self.weighted_n_left * impurity_left
      )
  
imports: from abc import ABC, abstractmethod
  import ivy
label_desc: Use image node_id 4 for calling the Criterion obj's underlying member method code with example usage: obj.proxy_impurity_improvement() and returns: unknown