code: def _mkstemp_inner(dir, pre, suf, flags):
      
  
      names = _get_candidate_names()
  
      for seq in range(TMP_MAX):
          name = next(names)
          file = _os.path.join(dir, pre + name + suf)
          try:
              fd = _os.open(file, flags, 0o600)
              return (fd, _os.path.abspath(file))
          except FileExistsError:
              continue    # try again
          except PermissionError:
              # This exception is thrown when a directory with the chosen name
              # already exists on windows.
              if _os.name == 'nt':
                  continue
              else:
                  raise
  
      raise FileExistsError(_errno.EEXIST,
                            "No usable temporary file name found")
docs: Code common to mkstemp, TemporaryFile, and NamedTemporaryFile.