def check_environ():
    """Ensure that 'os.environ' has all the environment variables we
    guarantee that users can use in config files, command-line options,
    etc.  Currently this includes:
      HOME - user's home directory (Unix only)
      PLAT - description of the current platform, including hardware
             and OS (see 'get_platform()')
    """
    if os.name == 'posix' and 'HOME' not in os.environ:
        try:
            import pwd

            os.environ['HOME'] = pwd.getpwuid(os.getuid())[5]
        except (ImportError, KeyError):
            # bpo-10496: if the current user identifier doesn't exist in the
            # password database, do nothing
            pass

    if 'PLAT' not in os.environ:
        os.environ['PLAT'] = get_platform()
Ensure that 'os.environ' has all the environment variables we
    guarantee that users can use in config files, command-line options,
    etc.  Currently this includes:
      HOME - user's home directory (Unix only)
      PLAT - description of the current platform, including hardware
             and OS (see 'get_platform()')
    
product/gradle-plugin/src/main/python/setuptools/_distutils/util.py