Cannot check whether SSHClient is still connected

[xdom]

It would be useful if we could somehow check whether SSHClient is still connected to a host. Sometimes it's not desirable to close and reopen connection after and before every command execution / file operation. However, host could be rebooted in the meanwhile and the ssh connection could be lost. In that case, we want to check if the connection is alive and if it's not, reconnect again.