code: def _get_default_tempdir():
      
  
      namer = _RandomNameSequence()
      dirlist = _candidate_tempdir_list()
  
      for dir in dirlist:
          if dir != _os.curdir:
              dir = _os.path.abspath(dir)
          # Try only a few names per directory.
          for seq in range(100):
              name = next(namer)
              filename = _os.path.join(dir, name)
              try:
                  fd = _os.open(filename, _bin_openflags, 0o600)
                  try:
                      try:
                          with _io.open(fd, 'wb', closefd=False) as fp:
                              fp.write(b'blat')
                      finally:
                          _os.close(fd)
                  finally:
                      _os.unlink(filename)
                  return dir
              except FileExistsError:
                  pass
              except OSError:
                  break   # no point trying more names in this directory
      raise FileNotFoundError(_errno.ENOENT,
                              "No usable temporary directory found in %s" %
                              dirlist)
docs: Calculate the default directory to use for temporary files.
      This routine should be called exactly once.
  
      We determine whether or not a candidate temp dir is usable by
      trying to create and write to a file in that directory.  If this
      is successful, the test file is deleted.  To prevent denial of
      service, the name of the test file must be randomized.