code: def _make_inc_temp(self, suffix="", prefix="", directory_name="/tmp/ray"):
          
          directory_name = os.path.expanduser(directory_name)
          index = self._incremental_dict[suffix, prefix, directory_name]
          # `tempfile.TMP_MAX` could be extremely large,
          # so using `range` in Python2.x should be avoided.
          while index < tempfile.TMP_MAX:
              if index == 0:
                  filename = os.path.join(directory_name, prefix + suffix)
              else:
                  filename = os.path.join(directory_name,
                                          prefix + "." + str(index) + suffix)
              index += 1
              if not os.path.exists(filename):
                  # Save the index.
                  self._incremental_dict[suffix, prefix, directory_name] = index
                  return filename
  
          raise FileExistsError(errno.EEXIST,
                                "No usable temporary filename found")
docs: Return a incremental temporary file name. The file is not created.
  
          Args:
              suffix (str): The suffix of the temp file.
              prefix (str): The prefix of the temp file.
              directory_name (str) : The base directory of the temp file.
  
          Returns:
              A string of file name. If there existing a file having
                  the same name, the returned name will look like
                  "{directory_name}/{prefix}.{unique_index}{suffix}"