code: def _env_set(name, value):
      """
        Sets the given environment variable value or unsets it, if the value is
      None.
  
      """
      if value is None:
          _env_del(name)
      else:
          os.environ[name] = value
  
file_path: turicreate/src/external/boost/boost_1_68_0/tools/build/test/configuration.py
imports: import BoostBuild
  import TestCmd
  import os
  import os.path
  import re
label_desc: Use image node_id 4 for calling a global function with example usage: _env_set(name, value) without return types