code: def SetEnvVar(env_var, value):
      """Sets/unsets an environment variable to a given value."""
  
      if value is not None:
          environ[env_var] = value
      elif env_var in environ:
          del environ[env_var]
  
file_path: googletest/googletest/test/gtest_test_utils.py
imports: import os
  import subprocess
  import sys
  import atexit
  import shutil
  import tempfile
  import unittest
label_desc: Use image node_id 1 for calling a global function with example usage: SetEnvVar(env_var, value) without return types