code: def all_test_env_combinations(n):
      """
      For a dataset with n >= 3 envs, return all combinations of 1 and 2 test
      envs.
      """
      assert n >= 3
      for i in range(n):
          yield [i]
          for j in range(i + 1, n):
              yield [i, j]
  
imports: import argparse
  import copy
  import hashlib
  import json
  import os
  import shlex
  import shutil
  import sys
  import numpy
  import tqdm
  from domainbed import algorithms
  from domainbed import command_launchers
  from domainbed import datasets
  from domainbed.lib import misc
label_desc: Use image node_id 1 for calling a global function with example usage: all_test_env_combinations(n) without return types