fromspackimport*classDttop(Package):"""Package with a complicated dependency tree"""homepage="http://www.example.com"url="http://www.example.com/dttop-1.0.tar.gz"version('1.0','0123456789abcdef0123456789abcdef')depends_on('dtbuild1',type='build')depends_on('dtlink1')depends_on('dtrun1',type='run')definstall(self,spec,prefix):pass