def _gen_back(self):
        back = set()
        if self.backends:
            for backend in self.backends:
                fun = '{0}.targets'.format(backend)
                if fun in self.rosters:
                    back.add(backend)
            return back
        return sorted(back)
Return a list of loaded roster backends
dataset/ETHPy150Open saltstack/salt/salt/roster/__init__.py/Roster._gen_back