sudo add-apt-repository ppa:kubuntu-ppa/ppa
 Updates for Kubuntu releases which are due to go to Ubuntu Updates.  Mostly KDE point releases.
 More info: https://launchpad.net/~kubuntu-ppa/+archive/ubuntu/ppa
Press [ENTER] to continue or Ctrl-c to cancel adding it.

gpg: keybox '/tmp/tmp4wdgwu15/pubring.gpg' created
gpg: /tmp/tmp4wdgwu15/trustdb.gpg: trustdb created
gpg: key 2836CB0A8AC93F7A: public key "Launchpad Kubuntu Updates" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:               imported: 1                                                                                                                                                            
OK