Remove any is_a edges that contain user-specified edges.

def _rm_gos_edges(rm_goids, edges_all):
        """Remove any is_a edges that contain user-specified edges."""
        edges_reduced = []
        for goid_child, goid_parent in sorted(edges_all, key=lambda t: t[1]):
            if goid_child not in rm_goids and goid_parent not in rm_goids:
                edges_reduced.append((goid_child, goid_parent))
        return edges_reduced