object.c:830
static VALUE
rb_mod_attr(argc, argv, klass)
    int argc;
    VALUE *argv;
    VALUE klass;
{
    VALUE name, pub;

    rb_scan_args(argc, argv, "11", &name, &pub);
    rb_attr(klass, rb_to_id(name), 1, RTEST(pub), Qtrue);
    return Qnil;
}
