For instance you can train them to sit down and stop barking on your commands when you have guests at home. (lovelybordercollie.com)
These dogs make their companions feel safe, retrieve objects, turn on and off light switches, bark on command for help, and many other tasks. (guidingeyes.org)
Do not be angry if barking on command is never part of your dog's repertoire! (pethelpful.com)