How to use the rpg.plugin_engine.PluginEngine function in rpg

def setUp(self):
        self.plugin_engine = PluginEngine(self.spec, self.sack)

def run_compiled_source_analysis(self):
        """executed in background after patches are applied"""
        self._plugin_engine.execute_phase(PluginEngine.phases[2],
                                          self.compiled_dir)

def load_plugins(self):
        """ This method sets up plugin engine and loads them """
        self._plugin_engine = PluginEngine(self.spec, self.sack)
        self._plugin_engine.load_plugins(
            Path('rpg/plugins'),
            self.conf.exclude)
        for directory in self.conf.directories:
            self._plugin_engine.load_plugins(
                Path(directory),
                self.conf.exclude)