code: def done_indices(dones):
      """Calculates the indices where dones has True."""
      return np.argwhere(dones).squeeze(axis=1)
  
file_path: tensor2tensor/tensor2tensor/envs/env_problem_utils.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import functools
  import time
  import gym
  import numpy
  from tensor2tensor.envs import gym_env_problem
  from tensor2tensor.envs import rendered_env_problem
  from tensor2tensor.rl import gym_utils
label_desc: Use image node_id 1 for calling a global function with example usage: done_indices(dones) and returns: np