$ sudo apt-get build-dep sage
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages have unmet dependencies:
  libsdl1.2-dev: Depends: libpulse-dev but it is not going to be installed
                 Depends: libdirectfb-dev (>= 0.9.22) but it is not going to be installed
                 Depends: libaa1-dev but it is not going to be installed
                 Depends: libcaca-dev but it is not going to be installed
E: Build-dependencies for sage could not be satisfied.