code: func (fs *FSLocalKeyStore) dirFor(proxyHost string, create bool) (string, error) {
  	dirPath := filepath.Join(fs.KeyDir, sessionKeyDir, proxyHost)
  
  	if create {
  		if err := os.MkdirAll(dirPath, profileDirPerms); err != nil {
  			fs.log.Error(err)
  			return "", trace.ConvertSystemError(err)
  		}
  	}
  
  	return dirPath, nil
  }
docs: // dirFor returns the path to the session keys for a given host. The value
  // for fs.KeyDir is typically "~/.tsh", sessionKeyDir is typically "keys",
  // and proxyHost typically has values like "proxy.example.com".
  //
  // If the create flag is true, the directory will be created if it does
  // not exist.