+#define be_ifg_cliques_begin(self, iter, buf) ((self)->impl->cliques_begin(self, iter, buf))
+#define be_ifg_cliques_next(self, iter) ((self)->impl->cliques_next(self, iter))
+#define be_ifg_cliques_break(self, iter) ((self)->impl->cliques_break(self, iter))