code: def get_child(self, action):
      if action not in self.children:
          self.env.set_state(self.state)
          obs, reward, done, _, _ = self.env.step(action)
          next_state = self.env.get_state()
          self.children[action] = Node(
              state=next_state,
              action=action,
              parent=self,
              reward=reward,
              done=done,
              obs=obs,
              mcts=self.mcts,
          )
      return self.children[action]
  
imports: import collections
  import copy
  import math
  import numpy
label_desc: Use image node_id 11 for calling the Node obj's underlying member method code with example usage: obj.get_child(action) and returns: self