/*
 * call-seq:
 *      caused_by_join? -> bool
 *
 * +true+ iff this membership message was caused by a new node joining
 * a group.
 */
static VALUE
memb_caused_by_join(VALUE obj)
{
    struct SpreadMessage *sp_mess;

    Data_Get_Struct(obj, struct SpreadMessage, sp_mess);
    return INT2BOOL(Is_caused_join_mess(sp_mess->service_type));
}