off_event

static VALUE
fev_off_event(int argc, VALUE *argv, VALUE self)
{
    VALUE event = Qnil;
    VALUE events;

    rb_scan_args(argc, argv, "01", &event);
    if(!NIL_P(event)) {
        if(!RB_TYPE_P(event, T_STRING) && !RB_TYPE_P(event, T_SYMBOL)) {
            rb_raise(rb_eTypeError, "wrong argument type (expected String or Symbol)");
        }
        if (RB_TYPE_P(event, T_SYMBOL)) {
            event = rb_sym2str(event);
        }
    }
    events = rb_ivar_get(self, id_events);
    if (NIL_P(events)) {
        return Qnil;
    }
    ole_delete_event(events, event);
    return Qnil;
}