...
def source(name, dep, cmd):
myTrgCmd = '''
mkdir /sources;
cd /sources;
apt-get update;
[ ! -f .pkg.list ] &&
dpkg-query -f \'${binary:Package}\\n\' -W > .pkg.list;
apt-get install -y dpkg-dev;
cat .pkg.list | xargs -n 1 apt-get source'''
myHostCmd = 'tar -cf ../' + cmd[1].lstrip() + ' sources;'