code: func (c *Config) restSessionFile() (string, error) {
  	p, err := c.sessionFile()
  	if err != nil {
  		return "", err
  	}
  	return filepath.Join(c.RestSessionPath, p), nil
  }
docs: // restSessionFile is takes the session file name generated by sessionFile and
  // then prefixes the REST client session path to it.