root@ubuntu:~# apt-get install booktype
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
booktype : PreDepends: virtualenv but it is not installable
E: Unable to correct problems, you have held broken packages.
root@ubuntu:~#
root@ubuntu:~# apt-get install virtualenv
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package virtualenv is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'virtualenv' has no installation candidate
It looks like you're new here. If you want to get involved, click one of these buttons!