code: func (c *Client) ExportWatchingWalletAsync(account string) FutureExportWatchingWalletResult {
  	cmd := btcjson.NewExportWatchingWalletCmd(&account, btcjson.Bool(true))
  	return c.sendCmd(cmd)
  }
docs: // ExportWatchingWalletAsync returns an instance of a type that can be used to
  // get the result of the RPC at some future time by invoking the Receive
  // function on the returned instance.
  //
  // See ExportWatchingWallet for the blocking version and more details.
  //
  // NOTE: This is a btcwallet extension.