apt policy checkbox-gui
checkbox-gui:
  Installed: (none)
  Candidate: 1.2.4-0ubuntu1
  Version table:
     1.2.4-0ubuntu1 500
        500 http://pt.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        500 http://pt.archive.ubuntu.com/ubuntu xenial/main i386 Packages