How to use the monaco-languageclient/lib.BaseLanguageClient function in monaco-languageclient

createLanguageClient(language: string, connection: MessageConnection, services: BaseLanguageClient.IServices): BaseLanguageClient {
    return new BaseLanguageClient({
      name: `${language} language client`,
      clientOptions: {
        // use a language id as a document selector
        documentSelector: [language],
        // disable the default error handler
        errorHandler: {
          error: () => ErrorAction.Continue,
          closed: () => CloseAction.DoNotRestart
        }
      },
      services,
      // create a language client connection from the JSON RPC connection on demand
      connectionProvider: {
        get: (errorHandler, closeHandler) => {
          return Promise.resolve(createConnection(connection, errorHandler, closeHandler));
        }