code: def _reward(self):
      if self.state == 0:
          return self.left_state_reward
      elif self.state == self.chain_length - 1:
          return self.right_state_reward
      else:
          return 0
  
file_path: coach/rl_coach/environments/toy_problems/exploration_chain.py
imports: from enum import Enum
  import gym
  import numpy
  from gym import spaces
label_desc: Use image node_id 3 for calling the ExplorationChain obj's underlying member method code with example usage: obj._reward() and returns: self, self, int