eval.c:798
VALUE *
rb_svar(cnt)
    int cnt;
{
    struct RVarmap *vars = ruby_dyna_vars;
    ID id;

    if (!ruby_scope->local_tbl) return NULL;
    if (cnt >= ruby_scope->local_tbl[0]) return NULL;
    id = ruby_scope->local_tbl[cnt+1];
    while (vars) {
	if (vars->id == id) return &vars->val;
	vars = vars->next;
    }
    if (ruby_scope->local_vars == 0) return NULL;
    return &ruby_scope->local_vars[cnt];
}
