code: def exp_return_of_episode(episode):
      return sum(np.exp(x["reward"]) for x in episode)
  
imports: import collections
  import copy
  import os
  import tempfile
  import unittest
  import numpy
  import pytest
  import torch
  from pfrl import replay_buffer, replay_buffers
label_desc: Use image node_id 1 for calling a global function with example usage: exp_return_of_episode(episode) and returns: sum