Return a list of all GO IDs that are connected to edges.

def get_all_edge_nodes(self):
        """Return a list of all GO IDs that are connected to edges."""
        edge_nodes = set(e for es in self.edges for e in es)
        for edges in self.edges_rel.values():
            rel_nodes = set(e for es in edges for e in es)
            edge_nodes.update(rel_nodes)
        return edge_nodes